Questions tagged [8051]

The "8051" is a (still) very popular chip in the Intel MCS-51 micro controller series.

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8051 architecture doubt [closed]

Suppose twenty 8-bit integers belonging to the range {0, 1, 2, . . . , 127} are stored in memory locations 40H to 53H. Write an assembly language program to find the largest and second largest ...
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30 views

Understanding oscillation frequency for SAF-C509 processor

Good day. For the time being, I'm reversing automotive ECU which has Intel51 architecture processor - SAF-C509 by Infineon/Simens. Its command exection part has 6 states with 2 phases for each state. ...
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79 views

Encryption library for an 8051 microcontroller

I've programmed an 8051 microcontroller to send data out through an external transmitter (just a few bytes per transmission). I'm looking to encrypt this data in my microcontroller's program. I have a ...
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36 views

problem in programming ISR in 8051

in this code : ...
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49 views

Need more than two external interrupts in 8051

I am working with 8 YS-17 flame sensors and may need more in the future. There are only two INT0 and INT1 in port 3. Is there any way to get the other interrupts or I/Os to work as external ...
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88 views

Serial print in 8051

In this code: ...
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52 views

Is anyone familiar with EDsim? [closed]

I'm learning the basics of the microcontroller 8051 and I wrote a program that requires me to toggle a button situated in the ADC of the chip . Since I don't have the board , I worked on a software ...
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166 views

firmware testing methods

This is my first question here from the community :) So I have inherited some bad embedded code, the whole firmware is a messy spaghetti state-machine that has an infinite number of states! and it is ...
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43 views

How to use mode 0 in 8051?

I tried to use timer0 in mode 0 of AT89S52 for blinking a led for 1 second using this code: ...
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89 views

.c to .hex file conversion without using any IDE

I am new to microcontroller programming. I have a program written in C or assembly language which I need to convert into a .HEX file to flash into the 8051 microcontroller. I do not want to use an IDE ...
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53 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 ...
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88 views

Why 8051 microcontroller uses four different ports for I/O instead of using address bus and control signals

8051 has four ports for I/O .Therefore four peripherals can be connected to it at a time . My question is why doesn't it use the address bus to activate a specific peripheral ...and then use the data ...
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Cloning a 8051 flash with an Arduino

I have a 8051 microcontroller and want to copy the flash memory. I have an Arduino, a cp2102 usb to UART module and an 8051 microcontroller. The 8051 is a zen3309AD. How do I achieve this task. I ...
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30 views

What is the difference between ram and registers in 8051 vs arm v7?

Recently i am confused between the difference between ram and cpu registers.I have studied 8051 arch. and in that we had addressing for cpu registers in ram level (e.g. the adddress for R0 register in ...
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130 views

8051 to I2C backpack/4 bit LCD Byte Construct Probelms

Been feverishly writing bit bang code in assembly for this I2C backpack/4 bit LCD and dont quite understand the binary constructs I need to display text. Im trying to learn this the real way, not the ...
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76 views

What is a page in 8051 microprocessor?

https://www.hobbyprojects.com/8051_tutorial/acall_absolute_call.html I was learning about acall on the above website, but then came across the term page. What exactly is a page?
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How to program CH559 to use one USB as master the second one as slave?

I have found a video in youtube which uses CH559 to connect a normal mouse/keyboard or both at the same time in order to make inputs to arduino. These inputs can be visualized from the OLED ...
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70 views

How these timer values are derived?

I have a 8051 micro controller ,it has timer0,1,2,3 with different modes. in timer0,mode0, i got a sample code (as shown below). datasheet 8051 from that code ...
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60 views

In asynchronous communication how is the frequency same but clocks of both devices different?

Am currently studying 8051 microcontroller and in the course the lecturer told that in communication the frequencies of sender and receiver should be same else they will get different bits of data at ...
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1answer
278 views

What happens at hardware level when we feed a code? [duplicate]

I wanted to know what hardware is installed in 8051 such that whenever i write a program it accepts it and execute it. My query is what happens at the hardware level whenever i feed a program to 8051.
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98 views

Two switches and two LEDs using 8051

I am trying to work around a circuit and my requirement is as follows: - There are two inputs and two outputs. Each input controls an individual led. I am writing a code for this requirement using a ...
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46 views

minimizing waiting time for 8051 port state

I made myself a project with standard 8051 microcontrollers (AT89S52 and AT89C4051) and will be making more with the same due to price and availability. When data is being sent from one GPIO pin from ...
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47 views

ENC28j60 ethernet interfacing with efm8lb1 help needed

I am a newbie to ethernet controller. I went through ENC28j60 documentation But I couldn't find a proper example similar to my project. EFM8LB1 will read some sensor data (for example sensor data '...
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208 views

How can I code in a buzzer while using a 7-segment in an 8051

I'm currently working on a small queuing system where whenever someone presses a button (which I have linked to INT0), my 8051 would increase the register and would display a higher number on the dual ...
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72 views

Why does this driver not have a load resistor?

Im trying to drive a motor with this kind of circuit since my micro is an old 8051. The voltage I use is 5V and PowerV is also 5V. I also have a 56 ohm 1/2 watt resistor in series with my motor ...
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43 views

Weird error pattern on CC2541, the 8051 core

I am playing with the debug interface on the TI CC2541. It seems to be working fine, seeing correct chip ID etc. The interface has a DEBUG_INSTR command that lets you submit and execute an ...
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106 views

Grounding GPIO pins during 8051 programming

I'm trying to make a programmer for the 8051 microcontroller IC's, specifically the AT89C2051. I saw a circuit online (the blowit programmer) in which the unused GPIO pins are left floating. When the ...
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80 views

interrupt-on-change on 8051 microcontroller

I am trying to read the speed or number of rotations pulses of a self-made encoder motor. I am using an AT89C52 microcontroller. It gives external interrupt on rising or falling edge. How can I ...
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61 views

Chaging EA/VPP by software on Intel MCS-51/8051

I'm designing a circuit that uses the combined Program/Data bus from Intel MSC-51 as advantage. By the MCS-51 specification it has an internal 4K ROM and a EA/VPP pin that if set to high will access ...
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115 views

Converting “MPR121 capacitive keyboard” sensor filter data into capacitance values?

The project that I'm working on, the MPR121 capacitive touch sensing keyboard connected with a 8051 microcontroller, my first intention when I started implementing the project was to measure the ...
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8 channel quiz buzzer circuit using 8051 microcontroller

Project: 8 channel quiz buzzer circuit using 8051 microcontroller from this site. For the first candidate who presses their button, their number will show on the 7-segment display and the buzzer will ...
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ACK even for the not existing register, I2C problem!

I'm implementing this project with MPR121 keyboard communicating with 8051 via I2C before I get further into the program I wanted to know whether the sensor is communicating with the board, giving the ...
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113 views

8051 Open Drain Operation

While studying I ended up finding this question. Write the value (in hex) of the P1 after the execution of the code below. ...
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175 views

Assembler program showing ACK even with the wrong slave address, I2C code problem!

I have this project communicating MPR121 capacitive touch sensing keyboard with 8051 microcontroller, with some references I've implemented some I2C code for serial communication between master and ...
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49 views

How to check the flow of assembler instructions execution?

I'm creating a project that uses I2C serial communication in assembler and I'm having some issues transmitting data and receiving back so I thought I should somehow debug the whole program, besides ...
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52 views

Check if the slave is receiving data from microcontroller and transmitting back successfully, I2C?

I have this project where I have to communicate MPR121 touch sensor keyboard with 8051 microcontroller via I2C, I've implemented the code and when I execute it I don't really know whether slave is ...
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434 views

How to check whether a byte of 8 bits contains 1, assembler 8051?

I need to know how to check whether a byte contains a 1 for touch status in a MPR121 project, so if: 00000010 then pin 2 is touched 00000100 then pin 3 is touched How can I detect it? A ...
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709 views

8051 microcontroller problem to find execution time of part1 for a given code

For the below mentioned 8051 assembly code: Time elapse: MOV R0,#100 Part 1 \$ \quad \, \, \,\,\$ : MOV R1,#50 Part 2 \$ \quad \, \, \,\,\$ : MOV R2,#248 Part 3 \$ \quad \, \, \,\,...
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513 views

TMOD value for timer 1 in mode 0 in 8051 microcontroller

What will be result of this statement: MOV TMOD,#00H Will it set it to timer 0 in mode 0 or to timer 1 in mode 0? Other statements like: ...
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889 views

555 Clock Circuit - how to choose resistor value? [closed]

I need to design a 555 clock circuit to output a clock pulse of a specific frequency. The circuit I'm using is this one (from here): I've used this circuit before and it works fine but the website ...
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367 views

What is the XTAL clock used for in an 8051 microntroller?

I'm trying to design an 8051 microcontroller circuit which uses timers/counters, and the circuit I'm using for inspiration uses a clock generated using the XTAL1 and XTAL2 pins of the IC, shown in the ...
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220 views

Reset MCU with a 1-0 button

I am working on a silabs C8051 MCU. It has a sleep mode which should be woken up by a reset. The mcu should start working (wake up from sleep) when the button in connected to Ground (Otherwise it is ...
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132 views

old 80C31 circuit not working. EPROM data retention issue?

I have an old piece of pro-audio gear in for repair. It dates from 1990. It was a fairly high-end piece of gear at the time and still has some value so it is worth repairing. But the symptoms I see ...
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CC2530: adapting AVR/pgmspace.h for Zigbee

Goal: Adapt ENC28J60 codes written for ATMega328p (http://tuxgraphics.org/electronics/201204/embedded-ethernet-client.shtml) for CC2530. Problem: No equivalent library for AVR/pgmspace.h available ...
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69 views

minimalist serial port addon to a basic 8052

Currently I have two microcontrollers connected to each other so that I have two serial ports. One to the PC and one to a wireless radio module. Now I'm considering replacing one microcontroller with ...
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46 views

Bidirectional data bus divided into nibbles not returning correct data - 8051

Since I have 10 I/O lines connected between two microcontrollers (AT89C4051 + AT89S52), I am trying to get away with elegant data transfer. Instead of spending months redoing an entire circuit board, ...
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51 views

Byte-Banging 2 8051's using port addresses

Currently I have two microcontrollers setup in which entire ports are connected to each other (P1.1 connected to P1.1, P1.2 connected to P1.2, etc). I also have two pairs of extra GPIO pins connected ...
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49 views

Do some microcontrollers require data to be loaded in temporary memory before programming?

When I programmed the AT89Cx051 series of microcontrollers, I didn't have to use special memory to program the data, but now even though I'm following the instructions in the datasheet (found from ...
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37 views

Can this circuit produce 0, 5 and 12 volts in fixed increments for the AT89LP4052?

Due to the speed requirements of my project, I'm looking at replacing the AT89C4051 with an AT89LP4052 with some code modifications since it offers double the memory and 6x the speed for the same ...

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