Questions tagged [assembly]
This is a programming language that is at a low level that corresponds with the instruction set of the machine being programmed.
408
questions
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Battery made of Li-ion cells assembly
Do you see any issue (feasability, safery, ...) about assembling a battery pack with 10 Li-ion 3.7V 2600mAh cells (put in parallel) having their own individual protection circuits (overcharge and over ...
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0answers
44 views
Read after Write and Write after write dependencie at the same time
Assuming the following pseudo-code down bellow:
1)r1 = 4
2)r2 = 5
3)r3 = r1 + 5
4)r4 = r2 + r1
5)r4 = r4 + r3
6)r1 = 10
7)r7 = r1 - 1
the r4 on line 5 is both name ...
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3answers
87 views
4-bit mode of LCD-1602 using 8052 µc
I try writing "NO" in the LCD using 4-bit mode. So, I programmed the AT89S52 to send the upper nibble first to the last 4 data inputs of the LCD. I used AND operation to eliminate the lower ...
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56 views
Indirect addressing on an assembly program with RAM locations
Here, I have written a indirect addressing assembly program (with PIC18) to
copy following to RAM locations 10H to 16H.
(It says MERHABA in turkish (means hello)
But, I am not sure that the part of my ...
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2answers
37 views
AVR “OUT” function. addressing port without constant
I am currently writing some assembly code that needs to address different I/O ports at certain times in my code. For example, at one point I may want to address PORTD4, and at another point I may want ...
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1answer
64 views
Is the following 8085-based design I/O mapped or memory mapped?
The above picture is an 8085-based system schematic used for undergrad courses at the laboratory. Now at first sight it seems that the 8085 in the circuit is isolated mapped IO since it uses the IO/M' ...
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1answer
20 views
ST instruction of avr in microchip stuio (avr studio) nor working as expected
I am trying to understand indirect addressing in avr and tried the following code :
ldi r31, 0x28
ldi r26, 0x2c
ldi r27, 0x00
st X+, r31
when r26 and r27 are ...
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0answers
38 views
Offset of bnez in RISC-V program
I came across a question about assembly that I was confused on.
We are given the following table for addresses and instructions:
The question says: replace the labels of PC-relative targets with ...
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1answer
57 views
Going below the bottom of the stack in ATmega328P
I'm working with an AVR based project and just have one curiosity.
The ATmega328P has total 2kB of SRAM. The lowest address of the stack can be 0x8FF. Now suppose the stack pointer is at 0x8FF. What ...
2
votes
2answers
80 views
Microchip's pic-as throws syntax error on macro define
I have a file with a name like xxxx.asm
in it I have:
InitPORTA MACRO
pic-as throws a syntax error on this line.
The code ...
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0answers
25 views
AVR Assembly - Operations with two 8-bit registers in 16-bit two complement negative values
I have this code in which I try to multiply the given number by 4. I have two variants and that is that it is negative and positive, but it doesn't work for negative values, you don't know why?
...
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1answer
52 views
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1answer
96 views
Hi everyone, do somebody have experience with usb on assembly level for stm32? [closed]
Need a help with enumeration process, can't receive set_address from hub (PC). when answering to get device descriptor, getting reset but no set_address request only zero-length PKTSTS_SETUP_COMP->...
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2answers
42 views
BANKSEL problem with PIC16F18855
I'm working with PIC16F18855 and have some problem with select memory bank via BANKSEL. In listing I see strange message and it's not working properly.
...
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0answers
40 views
Help in understanding Store Word (SW) instruction in Risc-V
So this is what I understood from what my professor said, but I don't think it's the right answer. What am I doing wrong? I'm sure It's just some small thing that I'm getting mixed up.
Given ...
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1answer
41 views
Help understanding ARM Cortex-M4 SBC instruction
Page 88 of the ARM Cortex-M4 Generic User Guide says "The SBC instruction subtracts the value of Operand2 from the value in Rn. If the carry flag is CLEAR, the result is reduced by one." Why ...
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0answers
52 views
Why the assembly code does not match the number of cycles of ARM M4？
I ran the following C program on STM32F405 (ARM Cortex-m4). I tried to comprehend its computation period instruction-by-instruction.
...
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1answer
304 views
What is the difference in RISCV between JAL and JALR?
I'm kinda confused on what the difference is between the two instructions and would love a comparison of the two!
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1answer
87 views
Two microprocessors with same machine language and different assembly language [closed]
I need to find two microprocessors that have same machine language but different assembly language.
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1answer
137 views
PIC10F200 - blinking LED (pic-as) - Assembly
The code below worked for my 10F206, but now I use a 10F200 and for some reason the led
does not blink anymore. (compiler: pic-as 2.30, IDE: MPLAB X IDE 5.40)
It compiles but the led stays off.
...
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1answer
228 views
RISC-V assembly lui?
In RISC-V assembly I wrote:
addi s0,x0,0x20000
Is this legal such that the assembler will prove the command and make it work right or I'm forced to change it to:
<...
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0answers
49 views
Why we can't do forward in RiscV?
While studying forwarding in RiscV cpu I saw the following claim:
But I can't understand why we can't do forward in this case, why in different conditions we were able to do this and now we can't?
It ...
6
votes
1answer
102 views
ARM Cortex-M4 VFMA (fused multiply-add) performance? 3, 2 or 1 clock? Forwarding?
I am working on some performance-critical DSP code destined to run on an ARM Cortex-M4. One particular section of the code (a sinc interpolation function) is dense with multiply-accumulate operations ...
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votes
1answer
83 views
RiscV assembly, function arguments
I learnt that in RiscV assembly we save function arguments in registers s0,...,s7 but what if I had more that 8 arguments?
Plus what about the case where I have more than 32 arguments (let's say 40) ...
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votes
4answers
154 views
Why is bool type typically 1 byte long?
I was reading: https://www.quora.com/Why-is-the-bool-type-typically-8-bits-long
And the answer was:
Because it’s the smallest type that has an individual memory address
so that you can take a pointer ...
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0answers
56 views
How to assess worst case runtime and correctness of an assembly implementation?
Set off by a question on CodeReview, I revisited "8-bit AVR unsigned division".
Trying much the same as for below 8 bit/8 bit → Q, R implementation, I found assessment of cycle counts of an &...
3
votes
1answer
96 views
How can I improve my LED display code so that it reacts in real time
This is a carry on question from my previous one and I was wondering how I can go about improving my code, which currently has an extreme delay in outputting the numbers to the display and also not ...
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vote
0answers
40 views
How can I exit my lookup table routine with the desired value?
How can I get my code to work correctly when I include ADC conversion in it?
I have a working code that displays two digits on 2 LED displays using a p16f1829. However, a problem arises when I try to ...
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1answer
66 views
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0answers
104 views
How can I improve my buzzer application using a PIC16F1829
I am trying to improve my assembly code (see below) for PIC16F1829 by using a macro to set up the parameters to play an audible sound.
My previous attempt had used a macro BEEP, which has now been ...
14
votes
2answers
2k views
Fiducial marks: Do they need to be a pad or is it okay if I use the top silk layer?
I have been advised by a more experienced engineer to integrate fiducial marks on my designs for P&P automatic assembly referencing, but he didn't say how to do it exactly.
I googled it, and I see ...
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2answers
2k views
Assembly code, what does it do?
I'm interested to know what this assembly code do knowing that X1 is full of zeroes.
...
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1answer
29 views
Will assigning a value to the W-reg in PIC16F84A during an interrupt, save it after the interrupt is disabled?
Okay so, I'm having this part of my program that needs a value to be checked to continue.
basically, here is what it is doing:
...
0
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1answer
116 views
How to use PIC16F84A TMR0 Interrupt as a substitute to the Sleep instruction in Assembly
I have this circuit:
So my problem is that I'm having trouble using the TMR0 interrupt as a delay or substitute to the SLEEP instruction in the PIC16F84A. I can't quite get the concept of using the ...
0
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1answer
105 views
What is the fastest (in clock cycles) 16-bit x 16-bit unsigned integer division algorithm that will run on an ATMEGA1284?
What is the fastest (in clock cycles) division algorithm that will run on an ATMEGA1284?
The dividend is an unsigned 16-bit number passed into the algorithm in a pair of 8-bit registers.
The divisor ...
0
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1answer
62 views
Why is OUT0 incorrect?
The input frequency is 2 MHz and the output should be 2 kHz since I used mode 3 and the initial count value N=1000d.
The output frequency is 500kHz.
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1answer
277 views
Ethernet Communication with Microcontroller
I am trying to make Ethernet communication with MCU. To make this happen, I need MCU(in this case AT89C2051), Ethernet Controller ( ENC28J60), and a RJ45. However the microcontroller that I selected ...
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38 views
How do you do Electro-mechanical Assembly Documentation?
I realize this isn't specifically EE theory related, but I hope EE documentation advice falls within the scope of this forum!
For example, I have an enclosure from a mechanical engineer, and their ...
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2answers
435 views
What does JB instruction mean in Assembly
I am looking at an ST7066U controller for a 2x16 LCD, and in their datasheet, they have these Assembly instructions that I would like to change to C code.
...
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0answers
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How to safely set/clear only some bits of SCB->SHCSR on ARM Cortex-M processors?
On p. 265 of the third edition of Joseph Yiu's The Definitive Guide to Arm Cortex-M3 and Cortex-M4 Processors, there is some discussion about the "system handler control and state register" (...
2
votes
1answer
74 views
What is “activity” in solder flux?
I'm trying to select a solder flux and so many references (and one or two SE questions) discuss the types and differences. They mention "activity", such as "Rosin Activated (RA) flux ...
2
votes
1answer
61 views
How to know component's offset when making custom footprint
First of all, I'm using KiCAD, but I guess the same problematic exists in any layout software.
When I need to create a custom footprint for an SMD component, I only set the coordinates of whatever ...
0
votes
1answer
69 views
imm8 in ARM data-processing instruction
In ARM,
Data-processing instructions have an unusual immediate representation involving an 8-bit unsigned immediate, imm8, and a 4-bit rotation, rot. imm8 is rotated right by 2 × rot to create a 32-...
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vote
1answer
64 views
Why does the AVR Assembler linker think my data table is at the wrong address?
MCU: ATmega1284
Programmer: JTAGICE3
IDE: Atmel Studio 7.0.2397
Language: AVR Assembler
I have a constant data table in flash memory. The linker thinks it is located at address 0x0090, so when I ...
0
votes
1answer
287 views
Why is there no NOR with immediate value in MIPS? AKA NORI
One thing which got me thinking was the lack of NORI in MIPS. Is the argument similar to why there is no SUB for immediate values since it can be simulated with a different instruction? If so, how is ...
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vote
1answer
78 views
Why does carry flag change from 1 to 0 after ADDS?
While doing my homework on ARM controllers and assembly programming, I stumbled upon a confusing question.
So here's the line of code which I don't understand (there are other codes before and after ...
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vote
1answer
248 views
Expression calculated at assembly time
I don't understand the explanation. Doesn't the assembler have to calculate 3 * 4 + 5 so it takes longer to execute? Also since 3 * 4 +5 has more characters why does it not take more storage?
From ...
3
votes
1answer
64 views
AVR: do I have to wait for the internal pullup to stabilize?
speaking of an ATMega2560 (not Arduino!), I connected a simple push-button between PB6 and GND.
There is a bootloader and ...
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0answers
106 views
Linking and the ELF - use of PC-relative addressing, GOT and PLT
So that we're on the same page, I'll try to explain what I think I know about Symbol Relocation and ask questions as they come up.
Symbol Relocation:
Absolute addresses – replace the reference for ...
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1answer
77 views
8051 initializing data in external memory
I am trying to understand the use of external memory with an 8051. When you are using external memory with something like C8051F962 where you have to configure the ports to access the memory, how do ...
