Documentation-ATmega microcontroller - Revision history

Gippgig: fix typo

2019-10-21T23:11:23Z

fix typo

← Older revision		Revision as of 23:11, 21 October 2019
Line 83:		Line 83:
	If Vcc is correct check the voltage at pin 9. If it is not 0 find & fix the problem and repeat the check. If it is 0 turn off power, connect the rest of the circuit, & turn on power. Check pin 9 again; if it is not 0 shut off power, find & fix the problem, & repeat the check. If it is 0 repeat the check of Vcc. If Vcc is not correct fix the problem, repeat the check of pin 9, & then test Vcc again. If Vcc is correct see if the circuit works.		If Vcc is correct check the voltage at pin 9. If it is not 0 find & fix the problem and repeat the check. If it is 0 turn off power, connect the rest of the circuit, & turn on power. Check pin 9 again; if it is not 0 shut off power, find & fix the problem, & repeat the check. If it is 0 repeat the check of Vcc. If Vcc is not correct fix the problem, repeat the check of pin 9, & then test Vcc again. If Vcc is correct see if the circuit works.

	The ATmega328P Microcontroller - 2 Adding a self-test - Oct. 4, 2019 version		The ATmega328P Microcontroller - 2 Adding a self-test - Oct. 21, 2019 version
	The self-test works by checking whether the pins have the expected values. Note that the value of PIN should equal the value of PORT for output pins unless a pin is heavily loaded (which should generally be avoided and always avoided at higher Vcc); this is also the case for unused pins with the pullup enabled & unused pins with the pullup off if pulled down to Gnd (i.e., pin 10 below). Unless it would cause something bad to happen to whatever the microcontroller is controlling, the test should be repeated with each output pin set to both 0 & 1 to detect excessively low resistance to either Vcc or Gnd and adjacent pins should have opposite values to detect shorts between pins. Using the previous example, suppose that pin 1 is reset, 2 is an input with pullup on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-16 are outputs with 11-13 set to 1, 17-19 are unused, & 23-28 are inputs with pullups on for 24-25. Pin 2 should initially be 0, pin 6 is heavily loaded, pin 9 must not be set to 1 & has a resistor to Gnd, pin 10 also has a resistor to Gnd, pin 16 is the self-test output (0=fail, 1=pass), pin 23 is an analog input, pin 24 should initially be 1 & pin 27 0, & pin 28 should be the same as pin 26 until the self-test sets pin 12 to 1. Note that the self-test momentarily sets pin 16 to 0 so this must not trigger an error response. Here is the port bit map; 3 values are given for PORTB (the first 2 being the values used for self-testing with the 2nd also being the final value if the self-test passes (there is no need to change it since pin 16 is already 1 & 14-15 don't need to be set to a particular value) while the 1st (pin 16 already 0) or 3rd is the final value if the self-test fails) & 3 values are given for PORTD (the first 2 again being the values used for self-testing & the 3rd the final value that sets the outputs to the correct values).		The self-test works by checking whether the pins have the expected values. Note that the value of PIN should equal the value of PORT for output pins unless a pin is heavily loaded (which should generally be avoided and always avoided at higher Vcc); this is also the case for unused pins with the pullup enabled & unused pins with the pullup off if pulled down to Gnd (i.e., pin 10 below). Unless it would cause something bad to happen to whatever the microcontroller is controlling, the test should be repeated with each output pin set to both 0 & 1 to detect excessively low resistance to either Vcc or Gnd and adjacent pins should have opposite values to detect shorts between pins. Using the previous example, suppose that pin 1 is reset, 2 is an input with pullup on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-16 are outputs with 11-13 set to 1, 17-19 are unused, & 23-28 are inputs with pullups on for 24-25. Pin 2 should initially be 0, pin 6 is heavily loaded, pin 9 must not be set to 1 & has a resistor to Gnd, pin 10 also has a resistor to Gnd, pin 16 is the self-test output (0=fail, 1=pass), pin 23 is an analog input, pin 24 should initially be 1 & pin 27 0, & pin 28 should be the same as pin 26 until the self-test sets pin 12 to 1. Note that the self-test momentarily sets pin 16 to 0 so this must not trigger an error response. Here is the port bit map; 3 values are given for PORTB (the first 2 being the values used for self-testing with the 2nd also being the final value if the self-test passes (there is no need to change it since pin 16 is already 1 & 14-15 don't need to be set to a particular value) while the 1st (pin 16 already 0) or 3rd is the final value if the self-test fails) & 3 values are given for PORTD (the first 2 again being the values used for self-testing & the 3rd the final value that sets the outputs to the correct values).
	B7 10 0 0 0 0 unused, resistor to Gnd		B7 10 0 0 0 0 unused, resistor to Gnd
Line 130:		Line 130:
	1010 F4B1 BRNE 16 PIND outputs not same as PORTD besides D4, fail, pin 16 already 0, go to 1027		1010 F4B1 BRNE 16 PIND outputs not same as PORTD besides D4, fail, pin 16 already 0, go to 1027
	1011 B176 IN R23,06 Load from PINC		1011 B176 IN R23,06 Load from PINC
	1012 ~~7E7A~~ ANDI R23,FA Clear unpredictable bits C0 & C2		1012 7F7A ANDI R23,FA Clear unpredictable bits C0 & C2
	1013 3072 CPI R23,02 Test for pass with C3=C5=0		1013 3072 CPI R23,02 Test for pass with C3=C5=0
	1014 F011 BREQ 02 Pass with C3=C5=0, go to 1017		1014 F011 BREQ 02 Pass with C3=C5=0, go to 1017

Gippgig: 2V

2019-10-05T20:19:42Z

← Older revision		Revision as of 20:19, 5 October 2019
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	If Vcc is correct check the voltage at pin 9. If it is not 0 find & fix the problem and repeat the check. If it is 0 turn off power, connect the rest of the circuit, & turn on power. Check pin 9 again; if it is not 0 shut off power, find & fix the problem, & repeat the check. If it is 0 repeat the check of Vcc. If Vcc is not correct fix the problem, repeat the check of pin 9, & then test Vcc again. If Vcc is correct see if the circuit works.		If Vcc is correct check the voltage at pin 9. If it is not 0 find & fix the problem and repeat the check. If it is 0 turn off power, connect the rest of the circuit, & turn on power. Check pin 9 again; if it is not 0 shut off power, find & fix the problem, & repeat the check. If it is 0 repeat the check of Vcc. If Vcc is not correct fix the problem, repeat the check of pin 9, & then test Vcc again. If Vcc is correct see if the circuit works.

	The ATmega328P Microcontroller - 2 Adding a self-test - ~~Sept~~. 30, 2019 version		The ATmega328P Microcontroller - 2 Adding a self-test - Oct. 4, 2019 version
	The self-test works by checking whether the pins have the expected values. Note that the value of PIN should equal the value of PORT for output pins unless a pin is heavily loaded (which should generally be avoided and always avoided at higher Vcc); this is also the case for unused pins with the pullup enabled & unused pins with the pullup off if pulled down to Gnd (i.e., pin 10 below). Unless it would cause something bad to happen to whatever the microcontroller is controlling, the test should be repeated with each output pin set to both 0 & 1 to detect excessively low resistance to either Vcc or Gnd and adjacent pins should have opposite values to detect shorts between pins. Using the previous example, suppose that pin 1 is reset, 2 is an input with pullup on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-16 are outputs with 11-13 set to 1, 17-19 are unused, & 23-28 are inputs with pullups on for 24-25. Pin 2 should initially be 0, pin 6 is heavily loaded, pin 9 must not be set to 1 & has a resistor to Gnd, pin 10 also has a resistor to Gnd, pin 16 is the self-test output (0=fail, 1=pass), pin 23 is an analog input, pin 24 should initially be 1 & pin 27 0, & pin 28 should be the same as pin 26 until the self-test sets pin 12 to 1. Note that the self-test momentarily sets pin 16 to 0 so this must not trigger an error response. Here is the port bit map; 3 values are given for PORTB (the first 2 being the values used for self-testing with the 2nd also being the final value if the self-test passes (there is no need to change it since pin 16 is already 1 & 14-15 don't need to be set to a particular value) while the 1st (pin 16 already 0) or 3rd is the final value if the self-test fails) & 3 values are given for PORTD (the first 2 again being the values used for self-testing & the 3rd the final value that sets the outputs to the correct values).		The self-test works by checking whether the pins have the expected values. Note that the value of PIN should equal the value of PORT for output pins unless a pin is heavily loaded (which should generally be avoided and always avoided at higher Vcc); this is also the case for unused pins with the pullup enabled & unused pins with the pullup off if pulled down to Gnd (i.e., pin 10 below). Unless it would cause something bad to happen to whatever the microcontroller is controlling, the test should be repeated with each output pin set to both 0 & 1 to detect excessively low resistance to either Vcc or Gnd and adjacent pins should have opposite values to detect shorts between pins. Using the previous example, suppose that pin 1 is reset, 2 is an input with pullup on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-16 are outputs with 11-13 set to 1, 17-19 are unused, & 23-28 are inputs with pullups on for 24-25. Pin 2 should initially be 0, pin 6 is heavily loaded, pin 9 must not be set to 1 & has a resistor to Gnd, pin 10 also has a resistor to Gnd, pin 16 is the self-test output (0=fail, 1=pass), pin 23 is an analog input, pin 24 should initially be 1 & pin 27 0, & pin 28 should be the same as pin 26 until the self-test sets pin 12 to 1. Note that the self-test momentarily sets pin 16 to 0 so this must not trigger an error response. Here is the port bit map; 3 values are given for PORTB (the first 2 being the values used for self-testing with the 2nd also being the final value if the self-test passes (there is no need to change it since pin 16 is already 1 & 14-15 don't need to be set to a particular value) while the 1st (pin 16 already 0) or 3rd is the final value if the self-test fails) & 3 values are given for PORTD (the first 2 again being the values used for self-testing & the 3rd the final value that sets the outputs to the correct values).
	B7 10 0 0 0 0 unused, resistor to Gnd		B7 10 0 0 0 0 unused, resistor to Gnd
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	After all the tests described previously pass, if the self-test does not pass measure the voltage at pin 16; if it is not 0 test the resistor & LED, make sure the LED isn't backwards, & check for a wiring error. If pin 16 is 0 connect a 2.7k resistor from pin 16 to Vcc; if it now reads >1V the pin apparently was not initialized to an output, check the program for errors (beware typos) & make sure it was loaded into the microcontroller correctly. If it still reads 0 the self-test really did fail.		After all the tests described previously pass, if the self-test does not pass measure the voltage at pin 16; if it is not 0 test the resistor & LED, make sure the LED isn't backwards, & check for a wiring error. If pin 16 is 0 connect a 2.7k resistor from pin 16 to Vcc; if it now reads >1V the pin apparently was not initialized to an output, check the program for errors (beware typos) & make sure it was loaded into the microcontroller correctly. If it still reads 0 the self-test really did fail.
	Check the voltages on all of the pins. Suppose that the supply is 2V & the voltages on pins 1-6 are 2,0,2,0,2,1, on 9-19 are 0,0,2,0,0,0,2,0,2,2,2, & 23-28 are .7,2,2,0,0,0. The odd value at pin 6 is not unexpected because of the heavy load and pin 23 is an analog input while 9-10 & 14-19 match the 1st test value for port B indicating that the first part of the self-test (at 100C) passed (but the test failed before PORTB was reloaded at 101A). Pins 23-28 match the expected value (pin 1 should be 2 because it's reset) for port C. Pins 2-6 & 11-13 match the 1st value for port D except for pin 13 (D7), which should be 2V but was 0. This indicates that pin 13 is shorted, check the wiring to that pin. On the other hand, if pins 12 & 13 were both .9V that would indicate that pins 12 & 13 are shorted together. Fix the problem & try again.		Check the voltages on all of the pins. Suppose that the supply is 2V & the voltages on pins 1-6 are 2,0,2,0,2,1, on 9-19 are 0,0,2,0,0,0,2,0,2,2,2, & 23-28 are .7,2,2,0,0,0. The odd value at pin 6 is not unexpected because of the heavy load and pin 23 is an analog input while 9-10 & 14-19 match the 1st test value for port B indicating that the first part of the self-test (at 100C) passed (but the test failed before PORTB was reloaded at 101A). Pins 23-28 match the expected value (pin 1 should be 2V because it's reset) for port C. Pins 2-6 & 11-13 match the 1st value for port D except for pin 13 (D7), which should be 2V but was 0. This indicates that pin 13 is shorted, check the wiring to that pin. On the other hand, if pins 12 & 13 were both .9V that would indicate that pins 12 & 13 are shorted together. Fix the problem & try again.
	If the self-test passes see if the circuit works.		If the self-test passes see if the circuit works.
	</nowiki>		</nowiki>

Gippgig: micro1 - BOOTRST

2019-10-03T23:52:55Z

micro1 - BOOTRST

← Older revision		Revision as of 23:52, 3 October 2019
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	Bobby		Bobby

	The ATmega328P Microcontroller - 1 Setting up the I/O pins - ~~Sept~~. 30, 2019 version		The ATmega328P Microcontroller - 1 Setting up the I/O pins - Oct. 3, 2019 version
	Note: In the following, the more negative voltage (Gnd) is 0 & the more positive voltage (Vcc) is 1. Addresses & data are given in hexadecimal.		Note: In the following, the more negative voltage (Gnd) is 0 & the more positive voltage (Vcc) is 1. Addresses & data are given in hexadecimal.
	The ATmega328P is one of a large family of similar 8-bit microcontrollers and can operate on 1.8 to 5.5 V. The data sheet is available at ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf (in the following the section describing an item is often given afterwards in parentheses, i.e. SREG(7.3.1)); the instruction set manual for this family is available at ww1.microchip.com/downloads/en/devicedoc/atmel-0856-avr-instruction-set-manual.pdf (note that the 328P does not have all of the instructions listed) & also see en.wikipedia.org/wiki/Atmel_AVR_instruction_set. Other members differ in various ways; consult their data sheets for details. The ATmega328P has 32 8-bit general purpose registers (which can also be addressed as data memory locations 0000-001F), 224 8-bit I/O registers (which can also be addressed as data memory locations 0020-00FF; note that 20 must therefore be added to the I/O register number when addressing it as memory), 2kx8 data RAM(8.3) (data memory locations 0100-08FF), a separate 16kx16 program flash memory(8.2) (note that while it is an 8-bit chip the instructions are 16 bits), & a separate 1kx8 EEPROM(8.4).		The ATmega328P is one of a large family of similar 8-bit microcontrollers and can operate on 1.8 to 5.5 V. The data sheet is available at ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf (in the following the section describing an item is often given afterwards in parentheses, i.e. SREG(7.3.1)); the instruction set manual for this family is available at ww1.microchip.com/downloads/en/devicedoc/atmel-0856-avr-instruction-set-manual.pdf (note that the 328P does not have all of the instructions listed) & also see en.wikipedia.org/wiki/Atmel_AVR_instruction_set. Other members differ in various ways; consult their data sheets for details. The ATmega328P has 32 8-bit general purpose registers (which can also be addressed as data memory locations 0000-001F), 224 8-bit I/O registers (which can also be addressed as data memory locations 0020-00FF; note that 20 must therefore be added to the I/O register number when addressing it as memory), 2kx8 data RAM(8.3) (data memory locations 0100-08FF), a separate 16kx16 program flash memory(8.2) (note that while it is an 8-bit chip the instructions are 16 bits), & a separate 1kx8 EEPROM(8.4).
Line 64:		Line 64:
	D1 3 1 0 out		D1 3 1 0 out
	D0 2 0 1 in, pullup on DDRD=FE PORTD=E1		D0 2 0 1 in, pullup on DDRD=FE PORTD=E1
	The following code fragment sets up the pins (in all code examples the program memory address is given first (4 hexadecimal digits) followed by the opcode (4 digits), the instruction, & an explanation). When power is turned on the processor resets and starts at address 0000(11.1). However, interrupts can cause execution to start nearby (for example, INT0 can cause execution to start at 0002(12.4)) so the first instruction is often a jump to get out of the way.		The following code fragment sets up the pins (in all code examples the program memory address is given first (4 hexadecimal digits) followed by the opcode (4 digits), the instruction, & an explanation). When power is turned on the processor resets and starts at address 0000(11.1) unless BOOTRST(27.6) has been programmed to 0. However, interrupts can cause execution to start nearby (for example, INT0 can cause execution to start at 0002(12.4)) so the first instruction is often a jump to get out of the way.
	0000 940C JMP		0000 940C JMP
	0001 1000 1000		0001 1000 1000

Gippgig: minor change

2019-09-30T20:25:28Z

minor change

← Older revision		Revision as of 20:25, 30 September 2019
Line 108:		Line 108:
	D1 3 1 1 0 0 out		D1 3 1 1 0 0 out
	D0 2 0 1 1 1 in, pullup on, initially 0 DDRD=FE PORTD=AB,55,E1		D0 2 0 1 1 1 in, pullup on, initially 0 DDRD=FE PORTD=AB,55,E1
	The following code fragment does the self-test ~~and sets up the pins~~.		The following code fragment sets up the pins & does the self-test.
	0000 940C JMP		0000 940C JMP
	0001 1000 1000		0001 1000 1000

Gippgig: minor change

2019-09-30T20:22:11Z

minor change

← Older revision		Revision as of 20:22, 30 September 2019
Line 41:		Line 41:
	0B PORTD		0B PORTD
	Suppose that pin 1 is reset, 2 is an input with the pullup resistor on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-15 are outputs with 11-13 set to 1, 16-19 are unused, & 23-28 are inputs with the pullups on for 24-25. Also suppose that setting pin 9 to 1 (except under special conditions) could damage the circuit; to reduce the chance of this happening this output is placed next to Gnd (pin 8), a resistor (~5k ohms suggested) is connected from the pin to Gnd, & the other adjacent pin (10) is unused & is connected thru a "pulldown" resistor (1k suggested) to Gnd instead of using the internal pullup. Here is the port bit map (the port bit is given first followed by the corresponding pin, the value of the DDR for that position, the value (if the value doesn't matter it is generally set to 0 in these examples) of the PORT for that position, & a description; after the last bit of a port the hexadecimal value of DDR & PORT is shown):		Suppose that pin 1 is reset, 2 is an input with the pullup resistor on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-15 are outputs with 11-13 set to 1, 16-19 are unused, & 23-28 are inputs with the pullups on for 24-25. Also suppose that setting pin 9 to 1 (except under special conditions) could damage the circuit; to reduce the chance of this happening this output is placed next to Gnd (pin 8), a resistor (~5k ohms suggested) is connected from the pin to Gnd, & the other adjacent pin (10) is unused & is connected thru a "pulldown" resistor (1k suggested) to Gnd instead of using the internal pullup. Here is the port bit map (the port bit is given first followed by the corresponding pin, the value of the DDR for that position, the value (if the value doesn't matter it is generally set to 0 in these examples) of the PORT for that position, & a description; after the last bit of a port the hexadecimal value of DDR & PORT is shown):
	B7 10 0 0 unused, resistor to Gnd		B7 10 0 0 unused, resistor to Gnd
	B6 9 1 0 out, =0, cannot be set to 1, resistor to Gnd		B6 9 1 0 out, =0, cannot be set to 1, resistor to Gnd
	B5 19 0 1 unused (set PORT to 1 to turn on pullup resistor)		B5 19 0 1 unused (set PORT to 1 to turn on pullup resistor)
	B4 18 0 1 unused		B4 18 0 1 unused
	B3 17 0 1 unused		B3 17 0 1 unused
	B2 16 0 1 unused		B2 16 0 1 unused
	B1 15 1 0 out		B1 15 1 0 out
	B0 14 1 0 out DDRB=43 PORTB=3C		B0 14 1 0 out DDRB=43 PORTB=3C
	C6 1 0 0 reset		C6 1 0 0 reset
	C5 28 0 0 in		C5 28 0 0 in
	C4 27 0 0 in		C4 27 0 0 in
	C3 26 0 0 in		C3 26 0 0 in
	C2 25 0 1 in, pullup on		C2 25 0 1 in, pullup on
	C1 24 0 1 in, pullup on		C1 24 0 1 in, pullup on
	C0 23 0 0 in DDRC=00 PORTC=06		C0 23 0 0 in DDRC=00 PORTC=06
	D7 13 1 1 out, =1		D7 13 1 1 out, =1
	D6 12 1 1 out, =1		D6 12 1 1 out, =1
	D5 11 1 1 out, =1		D5 11 1 1 out, =1
	D4 6 1 0 out		D4 6 1 0 out
	D3 5 1 0 out		D3 5 1 0 out
	D2 4 1 0 out		D2 4 1 0 out
	D1 3 1 0 out		D1 3 1 0 out
	D0 2 0 1 in, pullup on DDRD=FE PORTD=E1		D0 2 0 1 in, pullup on DDRD=FE PORTD=E1
	The following code fragment sets up the pins (in all code examples the program memory address is given first (4 hexadecimal digits) followed by the opcode (4 digits), the instruction, & an explanation). When power is turned on the processor resets and starts at address 0000(11.1). However, interrupts can cause execution to start nearby (for example, INT0 can cause execution to start at 0002(12.4)) so the first instruction is often a jump to get out of the way.		The following code fragment sets up the pins (in all code examples the program memory address is given first (4 hexadecimal digits) followed by the opcode (4 digits), the instruction, & an explanation). When power is turned on the processor resets and starts at address 0000(11.1). However, interrupts can cause execution to start nearby (for example, INT0 can cause execution to start at 0002(12.4)) so the first instruction is often a jump to get out of the way.
	0000 940C JMP		0000 940C JMP

Gippgig: minor changes

2019-09-30T20:04:24Z

minor changes

← Older revision		Revision as of 20:04, 30 September 2019
Line 3:		Line 3:
	Bobby		Bobby

	The ATmega328P Microcontroller - 1 Setting up the I/O pins - Sept. 29, 2019 version		The ATmega328P Microcontroller - 1 Setting up the I/O pins - Sept. 30, 2019 version
	Note: In the following, the more negative voltage (Gnd) is 0 & the more positive voltage (Vcc) is 1. Addresses & data are given in hexadecimal.		Note: In the following, the more negative voltage (Gnd) is 0 & the more positive voltage (Vcc) is 1. Addresses & data are given in hexadecimal.
	The ATmega328P is one of a large family of similar 8-bit microcontrollers and can operate on 1.8 to 5.5 V. The data sheet is available at ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf (in the following the section describing an item is often given afterwards in parentheses, i.e. SREG(7.3.1)); the instruction set manual for this family is available at ww1.microchip.com/downloads/en/devicedoc/atmel-0856-avr-instruction-set-manual.pdf (note that the 328P does not have all of the instructions listed) & also see en.wikipedia.org/wiki/Atmel_AVR_instruction_set. Other members differ in various ways; consult their data sheets for details. The ATmega328P has 32 8-bit general purpose registers (which can also be addressed as data memory locations 0000-001F), 224 8-bit I/O registers (which can also be addressed as data memory locations 0020-00FF; note that 20 must therefore be added to the I/O register number when addressing it as memory), 2kx8 data RAM(8.3) (data memory locations 0100-08FF), a separate 16kx16 program flash memory(8.2) (note that while it is an 8-bit chip the instructions are 16 bits), & a separate 1kx8 EEPROM(8.4).		The ATmega328P is one of a large family of similar 8-bit microcontrollers and can operate on 1.8 to 5.5 V. The data sheet is available at ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf (in the following the section describing an item is often given afterwards in parentheses, i.e. SREG(7.3.1)); the instruction set manual for this family is available at ww1.microchip.com/downloads/en/devicedoc/atmel-0856-avr-instruction-set-manual.pdf (note that the 328P does not have all of the instructions listed) & also see en.wikipedia.org/wiki/Atmel_AVR_instruction_set. Other members differ in various ways; consult their data sheets for details. The ATmega328P has 32 8-bit general purpose registers (which can also be addressed as data memory locations 0000-001F), 224 8-bit I/O registers (which can also be addressed as data memory locations 0020-00FF; note that 20 must therefore be added to the I/O register number when addressing it as memory), 2kx8 data RAM(8.3) (data memory locations 0100-08FF), a separate 16kx16 program flash memory(8.2) (note that while it is an 8-bit chip the instructions are 16 bits), & a separate 1kx8 EEPROM(8.4).
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	D1 3 1 0 out		D1 3 1 0 out
	D0 2 0 1 in, pullup on DDRD=FE PORTD=E1		D0 2 0 1 in, pullup on DDRD=FE PORTD=E1
	The following code fragment sets up the pins (in all code examples the program memory address is given first (4 hexadecimal digits) followed by the opcode (4 digits), the instruction, & an explanation). When power is turned on the processor resets and starts at address 0000(11.1). However, ~~other things~~ can cause execution to start nearby (for example, INT0 can cause execution to start at 0002(12.4)) so the first instruction is often a jump to get out of the way.		The following code fragment sets up the pins (in all code examples the program memory address is given first (4 hexadecimal digits) followed by the opcode (4 digits), the instruction, & an explanation). When power is turned on the processor resets and starts at address 0000(11.1). However, interrupts can cause execution to start nearby (for example, INT0 can cause execution to start at 0002(12.4)) so the first instruction is often a jump to get out of the way.
	0000 940C JMP		0000 940C JMP
	0001 1000 1000		0001 1000 1000
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	If Vcc is correct check the voltage at pin 9. If it is not 0 find & fix the problem and repeat the check. If it is 0 turn off power, connect the rest of the circuit, & turn on power. Check pin 9 again; if it is not 0 shut off power, find & fix the problem, & repeat the check. If it is 0 repeat the check of Vcc. If Vcc is not correct fix the problem, repeat the check of pin 9, & then test Vcc again. If Vcc is correct see if the circuit works.		If Vcc is correct check the voltage at pin 9. If it is not 0 find & fix the problem and repeat the check. If it is 0 turn off power, connect the rest of the circuit, & turn on power. Check pin 9 again; if it is not 0 shut off power, find & fix the problem, & repeat the check. If it is 0 repeat the check of Vcc. If Vcc is not correct fix the problem, repeat the check of pin 9, & then test Vcc again. If Vcc is correct see if the circuit works.

	The ATmega328P Microcontroller - 2 Adding a self-test - Sept. 29, 2019 version		The ATmega328P Microcontroller - 2 Adding a self-test - Sept. 30, 2019 version
	The self-test works by checking whether the pins have the expected values. Note that the value of PIN should equal the value of PORT for output pins unless a pin is heavily loaded (which should generally be avoided and always avoided at higher Vcc); this is also the case for unused pins with the pullup enabled & unused pins with the pullup off if pulled down to Gnd (i.e., pin 10 below). Unless it would cause something bad to happen to whatever the microcontroller is controlling, the test should be repeated with each output pin set to both 0 & 1 to detect excessively low resistance to either Vcc or Gnd and adjacent pins should have opposite values to detect shorts between pins. Using the previous example, suppose that pin 1 is reset, 2 is an input with pullup on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-16 are outputs with 11-13 set to 1, 17-19 are unused, & 23-28 are inputs with pullups on for 24-25. Pin 2 should initially be 0, pin 6 is heavily loaded, pin 9 must not be set to 1 & has a resistor to Gnd, pin 10 also has a resistor to Gnd, pin 16 is the self-test output (0=fail, 1=pass), pin 23 is an analog input, pin 24 should initially be 1 & pin 27 0, & pin 28 should be the same as pin 26 until the self-test sets pin 12 to 1. Note that the self-test momentarily sets pin 16 to 0 so this must not trigger an error response. Here is the port bit map; 3 values are given for PORTB (the first 2 being the values used for self-testing with the 2nd also being the final value if the self-test passes (there is no need to change it since pin 16 is already 1 & 14-15 don't need to be set to a particular value) while the 1st (pin 16 already 0) or 3rd is the final value if the self-test fails) & 3 values are given for PORTD (the first 2 again being the values used for self-testing & the 3rd the final value that sets the outputs to the correct values).		The self-test works by checking whether the pins have the expected values. Note that the value of PIN should equal the value of PORT for output pins unless a pin is heavily loaded (which should generally be avoided and always avoided at higher Vcc); this is also the case for unused pins with the pullup enabled & unused pins with the pullup off if pulled down to Gnd (i.e., pin 10 below). Unless it would cause something bad to happen to whatever the microcontroller is controlling, the test should be repeated with each output pin set to both 0 & 1 to detect excessively low resistance to either Vcc or Gnd and adjacent pins should have opposite values to detect shorts between pins. Using the previous example, suppose that pin 1 is reset, 2 is an input with pullup on, 3-6 & 9 are outputs with 9 set to 0, 10 is unused, 11-16 are outputs with 11-13 set to 1, 17-19 are unused, & 23-28 are inputs with pullups on for 24-25. Pin 2 should initially be 0, pin 6 is heavily loaded, pin 9 must not be set to 1 & has a resistor to Gnd, pin 10 also has a resistor to Gnd, pin 16 is the self-test output (0=fail, 1=pass), pin 23 is an analog input, pin 24 should initially be 1 & pin 27 0, & pin 28 should be the same as pin 26 until the self-test sets pin 12 to 1. Note that the self-test momentarily sets pin 16 to 0 so this must not trigger an error response. Here is the port bit map; 3 values are given for PORTB (the first 2 being the values used for self-testing with the 2nd also being the final value if the self-test passes (there is no need to change it since pin 16 is already 1 & 14-15 don't need to be set to a particular value) while the 1st (pin 16 already 0) or 3rd is the final value if the self-test fails) & 3 values are given for PORTD (the first 2 again being the values used for self-testing & the 3rd the final value that sets the outputs to the correct values).
	B7 10 0 0 0 0 unused, resistor to Gnd		B7 10 0 0 0 0 unused, resistor to Gnd

Gippgig: minor fixes

2019-09-30T20:00:35Z

minor fixes

Gippgig: introduction

2019-09-29T06:55:06Z

introduction

← Older revision		Revision as of 06:55, 29 September 2019
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	<nowiki>		<nowiki>
			This is an attempt to write documentation for the ATmega328P microcontroller (& learn to use it as I go along). Send corrections, suggestions, & comments to: gippgig@gmail.com
			Bobby

	The ATmega328P Microcontroller - 1 Setting up the I/O pins - Sept. 29, 2019 version		The ATmega328P Microcontroller - 1 Setting up the I/O pins - Sept. 29, 2019 version
	Note: In the following, the more negative voltage (Gnd) is 0 & the more positive voltage (Vcc) is 1. Addresses & data are given in hexadecimal.		Note: In the following, the more negative voltage (Gnd) is 0 & the more positive voltage (Vcc) is 1. Addresses & data are given in hexadecimal.

Gippgig: Gippgig moved page Documentation-AVR microcontroller to Documentation-ATmega microcontroller: better & overwrite old

2019-09-29T06:42:26Z

Gippgig moved page Documentation-AVR microcontroller to Documentation-ATmega microcontroller: better & overwrite old

← Older revision	Revision as of 06:42, 29 September 2019
(No difference)

Gippgig: Parts 1 & 2

2019-09-29T06:41:02Z

Parts 1 & 2

Show changes

← Older revision		Revision as of 20:00, 30 September 2019
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	1014 F011 BREQ 02 Pass with C3=C5=0, go to 1017		1014 F011 BREQ 02 Pass with C3=C5=0, go to 1017
	1015 327A CPI R23,2A Test for pass with C3=C5=1		1015 327A CPI R23,2A Test for pass with C3=C5=1
	1016 F481 BRNE 10 PORTC wrong, fail, pin 13 already 0, go to 1027		1016 F481 BRNE 10 PORTC wrong, fail, pin 16 already 0, go to 1027
	1017 E555 LDI R21,55 Load value to reverse D outputs		1017 E555 LDI R21,55 Load value to reverse D outputs
	1018 B95B OUT 0B,R21 Store into PORTD		1018 B95B OUT 0B,R21 Store into PORTD
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	1029... rest of program		1029... rest of program
	To turn on an LED if the self-test passes (recommended because it indicates that the initialization routine executed) connect the positive LED lead to pin 16 & the negative lead thru a resistor (the value depends on the voltage used) to Gnd. However, the LED may be too dim to see if the voltage is under 2V (test by connecting it directly from Vcc to Gnd (no resistor needed if under 2V)).		To turn on an LED if the self-test passes (recommended because it indicates that the initialization routine executed) connect the positive LED lead to pin 16 & the negative lead thru a resistor (the value depends on the voltage used) to Gnd. However, the LED may be too dim to see if the voltage is under 2V (test by connecting it directly from Vcc to Gnd (no resistor needed if under 2V)).
	To do more than just set pin 13 if the self-test fails, add additional code after 1026 & change the value of BREQ at 1025 to jump past the end of the added code. For example, this alternate ending will halt the program at the point the self-test failed to make it easier to find (as described below) the problem:		To do more than just set pin 16 if the self-test fails, add additional code after 1026 & change the value of BREQ at 1025 to jump past the end of the added code. For example, this alternate ending will halt the program at the point the self-test failed to make it easier to find (as described below) the problem:
	1025 F011 BREQ 02 Pass, go to 1028 (increased by 1 since 1 instruction added)		1025 F011 BREQ 02 Pass, go to 1028 (increased by 1 since 1 instruction added)
	1026 982A CBI 05,2 Set pin 16 to 0		1026 982A CBI 05,2 Set pin 16 to 0
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	1029 B95B OUT 0B,R21 Store into PORTD		1029 B95B OUT 0B,R21 Store into PORTD
	102A... rest of program		102A... rest of program
	(In this particular case only, it makes sense to also change the BRNE at 100C,1010,& 1016 to F7F9 BRNE 7F to halt the program at those points.)		In this particular case only, it makes sense to also change the BRNE at 100C,1010,& 1016 to F7F9 BRNE 7F to halt the program at those points.

	After all the tests described previously pass, if the self-test does not pass measure the voltage at pin 16; if it is not 0 test the resistor & LED, make sure the LED isn't backwards, & check for a wiring error. If pin 16 is 0 connect a 2.7k resistor from pin 16 to Vcc; if it now reads >1V the pin apparently was not initialized to an output, check the program for errors (beware typos) & make sure it was loaded into the microcontroller correctly. If it still reads 0 the self-test really did fail.		After all the tests described previously pass, if the self-test does not pass measure the voltage at pin 16; if it is not 0 test the resistor & LED, make sure the LED isn't backwards, & check for a wiring error. If pin 16 is 0 connect a 2.7k resistor from pin 16 to Vcc; if it now reads >1V the pin apparently was not initialized to an output, check the program for errors (beware typos) & make sure it was loaded into the microcontroller correctly. If it still reads 0 the self-test really did fail.
	Check the voltages on all of the pins. Suppose that the supply is 2V & the voltages on pins 1-6 are 2,0,2,0,2,1, on 9-19 are 0,0,2,0,0,0,2,0,2,2,2, & 23-28 are .7,2,2,0,0,0. The odd value at pin 6 is not unexpected because of the heavy load and pin 23 is an analog input while 9-10 & 14-19 match the 1st test value for port B indicating that the first part of the self-test (at 100C) passed (but the test failed before PORTB was reloaded at 101A). Pins 23-28 match the expected value (pin 1 should be 2 because it's reset) for port C. Pins 2-6 & 11-13 match the 1st value for port D except for pin 13 (D7), which should be 2V but was 0. This indicates that pin 13 is shorted ~~to Gnd~~, check the wiring to that pin. On the other hand, if pins 12 & 13 were 1V that would indicate that pins 12 & 13 are shorted together. Fix the problem & try again.		Check the voltages on all of the pins. Suppose that the supply is 2V & the voltages on pins 1-6 are 2,0,2,0,2,1, on 9-19 are 0,0,2,0,0,0,2,0,2,2,2, & 23-28 are .7,2,2,0,0,0. The odd value at pin 6 is not unexpected because of the heavy load and pin 23 is an analog input while 9-10 & 14-19 match the 1st test value for port B indicating that the first part of the self-test (at 100C) passed (but the test failed before PORTB was reloaded at 101A). Pins 23-28 match the expected value (pin 1 should be 2 because it's reset) for port C. Pins 2-6 & 11-13 match the 1st value for port D except for pin 13 (D7), which should be 2V but was 0. This indicates that pin 13 is shorted, check the wiring to that pin. On the other hand, if pins 12 & 13 were both .9V that would indicate that pins 12 & 13 are shorted together. Fix the problem & try again.
	If the self-test passes see if the circuit works.		If the self-test passes see if the circuit works.
	</nowiki>		</nowiki>