Arduino assembler8/26/2023 Simpler, and we do not need to store the previous and current values of If we can use the timer overflow interrupt flag, then the test is Ldi r20, 61 Initialize our software counterĬp r17, r18 Compare with previous valueīrsh check_timer unless the timer has decreased, repeatīrne check_timer if not zero, go back to checking the timer Ldi r16, PS_1024 Set r16 with prescaler 1024 value The code checks for timer 0 overflowingīy comparing its current value with the previous one.set PINB, 0x03 It as close as possible to yours, without using timer 1, nor interrupts,Īnd not even the interrupt flag. Without the “interrupt enable” bit, and check the interrupt flag in aīelow is a slightly simplified version of your program. Interrupts, you can configure counter 1 in much the same way, only Simplest would probably be to configure timer 1 to deliver an interruptĮvery second, and toggle the LED in the ISR. There are also quite a few ways the program could me made simpler. There is little point in resetting r20 once it has overflowed, as it.Then you should test the zero bit, as inc does not update the carry Better yet, increment with inc, as it's purpose is more obvious.Previous value of the carry bit to the target register. You should not increment a register with adc, but with plain add.īoth instructions update the carry bit, but adc also adds the.jwpat7 has already pointed out some of them, and here are Other than that, there are quite a few problems in the way you write Then you may want toĬompare TCNT0 with 61 instead of 128, in order to get closer to the Label, with something like out TCNT0, zero_reg. The simplest fix would be to reset TCNT0 right after the increment Than 128, it will continue to be larger than 128 for quite some time.ĭuring which time you are continuously incrementing your r20 counter. There is a bug with the logic of your program: once TCNT0 gets larger Out 0x05, r16 Set the LED to the new state Ldi r16, 0b00000000 Otherwise, change it to OFF Ldi r21, 1 Hold value 1 to increment r20Ĭpi r17, 128 Check to see if the timer is halfway done (1/2 second, max 255 value)īrbc 0, increment If r17 <= 128 (max 255 val before resets to 0), invert current LED stateĪdc r20, r21 Add r21 (1) to r20 (with carry)īrbs 0, reset If the carry branch is set, reset the registerĬpi r16, 0b00000000 Check if r16 is set to LED OFFīrbs 1, switchon If it is, change it to ON Am I doing something incorrectly? DDRB = 0x04 The goal is to have it blink for 1 second on, then 1 second off, however, it blinks incredibly quickly and is barely perceptible. Prototype PCB Shield For Arduino UNO R3 just 55c plus $1.I have an ATmega328P Arduino and am trying to make the LED blink using assembly without any additional includes. HD44780 1602 16x2 Serial LCD Black Character Green Backlight Display Board IIC PCF8574T I2C only £3.99 No specific links this week but here are few affiliate links that might earn my channel some money! Just click on them before buying ANYTHING from Banggood, Amazon or AliExpress! The ENTIRE assembler language manual (good luck with this one)ĪLL the function attributes eg attribute ((used)) (Special thanks to Michael Kurt Vogel for compiling this)ĭescription of the Arduino 8-bit and (psuedo) 16-bit registers Yes, really.ĭon't worry, I'm not expecting anyone to start writing assembler programs but it's so easy you might be tempted just to try it out. It's so easy to do write a simple Assembler sketch even beginners will find it straightforward, and it's an interesting look at how things "bolt together" behind the scenes. PCB Prototyping the easy way - see my video #129 for Hands-On details. See the associated YouTube video: įirst PCB order free! 2-sided PCB just $5 for 10 pieces. Sometimes a time-critical or sensor-specific piece of code needs to be run in Assembler - either written by you or a 3rd party.
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