Questions tagged [8051]

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

Filter by
Sorted by
Tagged with
0 votes
1 answer
47 views

Why 8051 is not detecting logic from circuit's voltage?

I am working on a ASK modulator and demodulator circuit which I wish to interface with a 8051 microcontroller to read serial data from demodulator circuit. The mod/demod circuit is developed and ...
Akshat Panda's user avatar
1 vote
0 answers
52 views

Why is this 8051 ASM code not working?

I’m trying to implement an automated parking lot using an 8051. I’m using stepper motors to function as gates at the entrance and the exit of the parking lot that open whenever the IR sensors placed ...
Captdeadpool's user avatar
1 vote
1 answer
57 views

Number of iterations in nested loop (8051)

Let's say we have this program: MOV R5, #4 H2: MOV R6, #10 H1: DJNZ R6, H1 DJNZ R5, H2 After moving the data to the registers, microcontroller executes ...
Agus's user avatar
  • 11
0 votes
3 answers
89 views

What is Multiprocessor Communication in 8051, and how to use it?

In 8051, one of the bit, SM2 or the D5 or SCON.5, is about "Used for Multiprocessor Communication." I am not clear about it. I watched quite many tutorials or explanations about 8051 on ...
AirCraft Lover's user avatar
0 votes
2 answers
170 views

Timer0 mode0 delay calculation for 11.0592 MHz crystal in 8051, ie, AT89C51

Lets generate a square wave of 2mSec period using an AT89C51 microcontroller with timer0 in mode0 on the P1.0 pin of port1. Assume xtal oscillator frequency of 11.0592 MHz. ...
Kat K's user avatar
  • 1
0 votes
0 answers
64 views

0.1μs delay for AT89C51

I need to follow WS2812B protocol, which requires communication with very high speed, like 0.4μs, 0.45μs, etc. Can I achieve it with AT89C51?
Sasisa Play's user avatar
1 vote
0 answers
114 views

AT89C51RD2 Empty or don't start up erratically

I have a strange problem and I don't know how to find a solution. I have a board with an AT89C51RD2 inside. I programmed it (thanks to Atmel flip), and it works fine. After some use (week or months), ...
F4F56's user avatar
  • 11
0 votes
0 answers
59 views

Inverting Arduino reset signal

I'm designing a general-purpose PCB for a 8051-family MCU. I make it compatible to use shields for the Arduino Uno. There is a snag with the reset circuitry, as an Arduino is active-low reset and the ...
Joe's user avatar
  • 187
0 votes
2 answers
109 views

Relay with AT89S52 microcontroller

I'm working on a project where I'm using 8051 microcontroller as a primary microcontroller which is interfacing with 4 relays. I have tested relays with two of my arduinos but when it comes to AT89S52 ...
Akash Patil's user avatar
0 votes
2 answers
131 views

Programming an 8051 MCU (Topro TP2808)

I have this 8051: I have acquired an it from an old device and I want to program it. I have experience with AVR, ESP, and STM microcontrollers, but not with 8051's. Googling info about this DIP IC, I'...
Kira's user avatar
  • 1
3 votes
2 answers
1k views

What is the correct way to connect resistors to a common-anode seven-segment display with a microcontroller?

What is the correct way to connect resistors to a seven-segment common-anode display with a microcontroller? Where should I connect a resistor? Here I am connecting a common anode display (common = +5 ...
Rahul.In's user avatar
1 vote
1 answer
313 views

Why is my 7-segment display not working when output modules (O3-O0) are connected to BCD to HEX converter module?

I have used an 8051 interfaced with an 8255 taking inputs from port A and port 1 and showing the output from port B AND C of the 8255. I also made a decoder for BCD to HEX (0-F). The input value is ...
Kakashi Hatake's user avatar
0 votes
1 answer
104 views

How to use external EEPROM (25AA320A) with the AT89S52 microcontroller over SPI

I am using the AT89S52-24PU as my MCU for a project where I need to read data from an EEPROM chip (in this case the 25AA320A serial EEPROM chip) over SPI. On the datasheet for the AT89S52 it says that ...
mrt's user avatar
  • 5
0 votes
0 answers
35 views

C8051F020 serial communication with GSM module (SIM900)

I am currently trying to interface the GSM900 module with a C8051F020 microcontroller using serial communication in order to send AT commands to the GSM from the 8051. The TX of the microcontroller is ...
Lesego Gareseitse's user avatar
-1 votes
1 answer
49 views

Problem with the output of the engine control signal

Program to control three DC motor levels and display speed (RPM) on a 7-segment LED using 8051. Use external interrupt 0 to read pulse from encoder. When compiling on keil C there is no error, but ...
Pumbaa's user avatar
  • 25
1 vote
2 answers
194 views

Keil C & 8051: DC Motor Speed Control & Display [closed]

I am writing a program to control three DC motor levels and display speed (RPM) on a 7-segment LED display using an 8051. I use an external interrupt to read pulse from encoder. When compiling, the ...
Pumbaa's user avatar
  • 25
0 votes
0 answers
33 views

problem with sd card video door phone

I'm working on the code of a video door phone and I'm trying to improve it. with 16 GB SD card the pictures that the camera takes can be seen on the LCD but when I connect the SD card to PC using a SD ...
salar1991's user avatar
0 votes
1 answer
499 views

Why we used 128 bytes internal RAM memory instead of 256 bytes in 8051?

... since using 7-bit in 8-bit address bus wastes one wire. In 8051 there is a 8-bit address bus for internal RAM out of which we just use 7 wires making it addressable to just 128 byte locations, why ...
Tanishq Chaudhary's user avatar
2 votes
1 answer
619 views

How decode serial data stream

I am trying to decode a data stream. This signal comes out of an STC 8H1K16 micro-controller. It is from the pin labeled TxD is the picture. When I trigger the signal I am trying to understand I get ...
Yepher's user avatar
  • 121
-1 votes
3 answers
356 views

8051 seven segment 1-9, and reset to 0

This is a university assignment, last part of 3. I cannot find any useful notes describing looping in the 8051 assembly language in the course resources, and the lecturer isn't replying to questions. ...
EmptyAtoms's user avatar
0 votes
2 answers
191 views

practical connection of LED to a MCU

While aiming to blink an led with this 8051 MCU, I used configuration 1 to connect my LED. It doesn't work. But 2 and 3 worked. logically, there should not be any reason behind why configuration 1 do ...
Sayan's user avatar
  • 739
2 votes
2 answers
695 views

8051 interrupt within interrupt high vs low priority

I am learning and experimenting on the 8051 (AT89C51). From what I have learnt so far regarding interrupts, I understand that an interrupt with a higher priority can interrupt an interrupt with a ...
shafik's user avatar
  • 59
1 vote
1 answer
192 views

8051 AT89C51 PSEN ALE pins, not to be used

I am new to microcontroller programming, and am about to lay hands on the 8051 AT89C51. I want to do some basic things like flashing LEDs, microcontroller to microcontroller data exchange etc. I have ...
shafik's user avatar
  • 59
1 vote
1 answer
94 views

timer mode 1 and edsim giving different result

IN 8051, Timer 0 in mode 1, if the maximum count reaches, the timer should displayed with 0000H, and should stay 0000h until we stop it and start again . But with this program ...
Sayan's user avatar
  • 739
0 votes
1 answer
698 views

8051 baud rate and timer connection

I was learning serial communication of 8051, in datasheet I have found this: it looks like both of the SBUF transmitter and SBUF receiver are parallel in serial out and serial in parallel out shift ...
Sayan's user avatar
  • 739
0 votes
1 answer
3k views

Max232 to DB9 connection confusion

The picture shows standard connection between 8051 and DB-9 via MAX232. 14th pin is the translated output of the transmitted data by 8051, so this should be connected to the receiver pin of DB-9, ...
Sayan's user avatar
  • 739
1 vote
1 answer
352 views

Frequency counting program - Timers in 8051

...
Sayan's user avatar
  • 739
1 vote
1 answer
133 views

A question on timers in 8051

Suppose the timer 1 of 8051 has finished counting, and raised TF1. Since it rolls back to 0, so currently TH1=00,TL1=00, and assume the bit TR1 is still set. At this moment, if we just clear the TF1 ...
Sayan's user avatar
  • 739
0 votes
1 answer
1k views

8051 timer delay calculation

In the following program MOV TMOD, #01H HERE: MOV TLO, #0F2H MOV THO, #0FFH CPL P1.2 ACALL DELAY SJMP HERE DELAY:SETB TR0 AGAIN: JB TF0,AGAIN CLR TF0 CLR TR0 RET ...
Sayan's user avatar
  • 739
0 votes
1 answer
898 views

Making a port as input in 8051

As we all know in order to make a port input in 8051 we have to write FFH to that. That is, MOV P1, #0FFH after this execution does it mean all the pins of the ...
Sayan's user avatar
  • 739
0 votes
1 answer
207 views

hex value is treated as decimal value

This is from Mazidi's book on microcontroller. As we can see we are aiming to add these two values 17H and 28H in HEX and want to get their sum in BCD, definitely their sum is 3F and which should be ...
Sayan's user avatar
  • 739
1 vote
1 answer
85 views

MCS-51 addressing memory with DPTR needs ACC

So as I have learnt the DPTR is used to store all of the 64k addresses of ROM space and RAM (according to our demand) so that we can use register indirect addressing through this 16 bit DPTR. Suppose ...
Sayan's user avatar
  • 739
0 votes
1 answer
125 views

8051 (AT89S51) on power on pin P3.0 output goes high for a brief moment

This is my first microcontroller project. Goal is to keep relay on for specified amount of time with pause and resume feature. I am using ports as follows: P1 to drive LCD 16x2 display. P0 and P2 to ...
the Hutt's user avatar
  • 149
1 vote
2 answers
2k views

8051 DPTR and program counter difference

So as we know both of the program counter and DPTR are 16bits in 8051 and hence both of them are capable of reaching 216 possible locations, which is sufficient for both RAM and ROM, then why DPTR is ...
Sayan's user avatar
  • 739
2 votes
1 answer
491 views

Registers in 8051 microcontroller

Recently I was reading about 8051 microcontroller instructions, and come to know that it has a set of registers from \$R_0 - R_7\$.Later on, when I was introduced with register banks then I feel like ...
Sayan's user avatar
  • 739
0 votes
3 answers
544 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 ...
Kiroloes Amir's user avatar
0 votes
3 answers
350 views

Finding maximum sink and source currents from datasheet

How can I find the maximum sinking and sourcing currents of different pins in a microcontroller (namely 8051) from its datasheet? Edit: I have downloaded and looked at the datasheet, I just can't read ...
Amir Soleimani's user avatar
0 votes
2 answers
3k views

How does the OV(Overflow flag) of the 8051 work and how does it differentiate between signed and unsigned digits?

If a number is 8 bit, the maximum value it can have is 2^8 or (1111 1111). In the OV flag, the last digit or the MSB decides the sign, but how does the overflow flag know if it is the "signed MSB&...
Circuit_Breaker0.7's user avatar
0 votes
1 answer
145 views

What is the difference between Register Addressing mode and Direct Addressing mode(8051)?

I find that there is no difference between the Register Addressing mode and the Direct Addressing mode. Can anyone tell the difference with respect to the 8051 microcontroller ?
Circuit_Breaker0.7's user avatar
1 vote
1 answer
93 views

8051 / EFM8LB1 / programming via C2 after PCON0.STOP := 1?

Yesterday I wanted to see, how much power my EFM8LB1 uses, when it has just this firmware with bootloader disabled: ...
RRIDDICC's user avatar
0 votes
0 answers
33 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. ...
Sergey Kanaev's user avatar
0 votes
1 answer
239 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 ...
J_Anderson's user avatar
0 votes
0 answers
56 views

problem in programming ISR in 8051

in this code : ...
Kiroloes Amir's user avatar
0 votes
1 answer
175 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 ...
Kiroloes Amir's user avatar
-1 votes
1 answer
86 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 ...
Samir's user avatar
  • 227
1 vote
2 answers
1k 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 ...
HussTale's user avatar
1 vote
1 answer
88 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: ...
Kiroloes Amir's user avatar
0 votes
1 answer
229 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 ...
Jay Sonawane's user avatar
0 votes
1 answer
253 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 ...
jchristiansen's user avatar
0 votes
3 answers
261 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 ...
Urooj's user avatar
  • 173

1
2 3 4 5 6