Hi everyone, I would like to share with the community an educational reflection on programming and microcontroller architecture. The Arduino ecosystem is extraordinary because it allows anyone to get a project up and running in minutes, thanks to the abstraction of C++. However, this high level of…

Complaining about nonexistent PORTA is same as complaining about why the ASM instruction only accepts certain numbers.

[image] westfw: Right there in locations 0-2, marked "reserved." You're right that there's nothing actually there so if put bbb 000,001,002 is executed but did nothink? this is avrlass.js [Screenshot_20260727_083536_Chrome]

Reserved bits should be written 0 - compatibility reasons. Probably nothing will happen if there is 1. PINC7 is reserved bit Reserved I/O memory addresses should never be written. The first one is 0x00 (0x20). Try it if you're not afraid. I think, nothing will happen. EDIT: I tried it in Atmel St…

[image] Budvar10: Reserved I/O memory addresses should never be written. The first one is 0x00 (0x20). Try it if you're not afraid. I think, nothing will happen. not want to try to modify for insert some custom instructions? i think that this assembler have already some custom functions! …

[image] Budvar10: EDIT: I tried it in Atmel Studio, nothing. Memory at 0x20 cannot be modified with STS, LDS returns 0. but 1001_1010_AAAA_Abbb what value return? sts is 16 bit like jmp? [Screenshot_20260727_160218_Chrome] with this table i think that is some easy to create your own comp…

i see that some users of this thread intervent in this thread but none did also me to intervent with asm!:grinning_face: [image] Timing - delay() and millis() I'm wondering if I can improve things by using millis() to make a timestamp, but even after consulting the Arduino doc for millis() I'm n…

[image] costycnc: but 1001_1010_AAAA_Abbb what value return? sts is 16 bit like jmp? Sorry, I don't understand. STS has 32-bit Opcode. No matter what, the byte at the address 0x20 stays 0x00. 0x20 is the first byte in 64 I/O register space and it is reserved. Of course, as I wrote, it was i…

[image] Budvar10: Sorry, I don't understand. STS has 32-bit Opcode. you are right ,i want did 32bit same as image [Screenshot_20260727_160218_Chrome] but you simulate ? not have a real atmega328 ? arduino nano/uno ?

Yes, it was simulation. I don't have anything usable with 328P right now. Almel Studio is pretty accurate. You try it. What's the worst that can happen?

[image] Budvar10: You try it. What's the worst that can happen? Nothing! I put also blink to d13 to verify if mcu is not blocking! But not! Led blinking , seem that mcu ignore sbi cbi 2,5 Certainly,D13 in this mode is with pullup , but i can see led blinking! [image] And disassemble: […

[Education] Demystifying Microcontrollers: Using ATmega328P and Assembly to Understand Registers

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costycnc July 27, 2026, 2:17pm 1537

i see that some users of this thread intervent in this thread but none did also me to intervent with asm!

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