Questions tagged [max232]

Anything related to the MAX232 integrated circuit. The MAX232 IC is used to convert serial communication signals using TTL levels, such as those produced by UARTs ICs, from and to standard RS-232 line signals.

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MAX3232: Switch between RS-232 and TTL levels

Sorry in advance, electronics noob here! I need to make a proof of concept to get some data out of third party system which handles both RS232 and TTL levels. The computer/raspberry/arduino shall - I ...
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4 votes
2 answers
411 views

MAX232 IC does not convert to and form RS232 levels

I made a simple circuit to read data from RS232 lines and print data on different RS232 lines. This is the IC I am using: MAX3232EIDWG4. The IC fails to convert the CMOS to RS232 level logic. I am ...
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3 votes
4 answers
365 views

RS-232 Crossover, and Protection against shorting two TXD lines

I'm in the process of designing a USB to RS-232 converter for communication with some existing boards, and I ran into two problems. First Question I need a way to programmatically reverse the TXD and ...
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3 answers
248 views

Configuring SPI circuit design for use in 485 transceiver for long range data transmission (50 meters plus)

So quickly getting out of things I have previously done however trying to send SPI controller signals across long ranges using either 18 AWG cable or based on all the recommendations we have been ...
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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, ...
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Doubts about Max232 IC chip

I have a Max 202 Ic and Max 232 Ic I currently want to make a USB to RS232 Serial Db9 converter i have the db9 male port, a max 232 and max 202 , usb female port and bunch of other passive components ....
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1 vote
1 answer
181 views

MAX233 problem with receiving data

I need to make serial connection between regular PCs and a 3.3v TTL device, I using the Maxim 233 which has internal capacitors. I have the PCs incoming TD connected to R1_IN and RD T1_OUT. The ground ...
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2 answers
162 views

Is it possible to use a MAX232 to convert 0 to 5V PWM to 0 to 12V PWM to input to a motor driver requiring 0 to 12V PWM logic?

I'd like to drive a 16kHz PWM signal at 0.5mA into the input of a motor driver expecting logic levels of 0V for LOW and 12V for HIGH, and expecting a PWM signal around this frequency. The PWM signal ...
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1 vote
1 answer
236 views

3.3V TTL to other formats and impedance matching [closed]

I am trying to convert a 3.3V 50 Ohm Impedance TTL Pulse-per-second into other formats (GPIB, USB, RS-232, etc.). I've found some format adapters/convertors like the MAX232, but I am either ...
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1 vote
0 answers
60 views

Ultrasonic dual transmitter-receiver circuit

I am building an ultrasonic flow sensor, based on piezoelectric actuators from cheap HR-SR04 modules. I need to measure the speed of sound back and forth. Schematic like this is good to send pulses: ...
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2 answers
340 views

Interfacing stm32 with MAX232

I am interfacing MAX232 with STM32F030k6. I have very recently found out that Max3232 would be a better choice, because it works with 3,3 volt. But I am eager to know if UART reciever pin of the ...
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Why use 100E resistor in max232 ic in serial pins 13 and 14?

serial pin 13(RxD) use 100E -pin 13 to male connector pin 2(RxD), serial pin 14(TxD) use 100E -pin 14 to male connector pin 3(TxD) Why 100E used? I have attached image and mention clearly for your ...
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3 answers
692 views

why use of 1uf capacitors in max232 ic, why does not use 10uf capacitor in max232 ic.?

I have use 1uf capacitor in max232 circuit c1=1uf (pin 1 and 3) c2=1uf (pin 4 and 5) c3=1uf (pin 2 and vcc) c4=1uf (pin 6 and gnd) c5=0.1uf (pin vcc and gnd) why this type of values used?
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Less noisy version of max232

After (mentally) banging my head at the wall wondering why my own circuit is glitchy after the PC communicates with it, I read some posts, and noticed others had very similar problems. All because the ...
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1 answer
783 views

Comparing MAX3232 vs MAX232 for line length

Which parameter in the datasheets of the line drivers MAX3232 and MAX232 can tell about the maximum length of the line for their correct operation if all else is same for the two circuits, that is ...
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Transmission from atmega32 to PC using max232 not working

Transmission from atmega32 to PC using max232 not working. When I checked the data from the Tx pin (in the realterm software) of atmega32 it was fine. But there was no output data from max232, when I ...
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2 answers
377 views

MAX232 vs TRS202EC Line Drivers

I have used MAX232 as UART serial line driver using 5V power supply. Now I have come across TRS202 chip in a circuit. It also run with 5V power supply. Does this chip has some special difference or is ...
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2 votes
1 answer
357 views

RS-232 interface chip problem - why is the voltage level so wrong?

1. What I want to do: I have a PCB with an AVR microcontroller (ATmega16U4) on it. I want the microcontroller to communicate with my computer through an RS-232 cable. 2. What I did: I added an ...
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4 votes
2 answers
578 views

Can a MAX232 IC be used for RS-232C standard?

I have a GT01 Panasonic LCD which it's interface is RS-232C. I have read that the difference between RS-232 and RS-232C is their voltage level which it's ±5 V in RS232C. Can I use a MAX232 IC to ...
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1 answer
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max232 charge pump problem

I have a problem with my MAX232 chip and can't find the solution. The schematic of the chip is in the attachment. The chip is soldered on to a PCB. I've checked all the connections, the supply ...
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1 answer
567 views

Can I use a MAX232 to communicate between a PIC and a Raspberry Pi?

I would like to send serial data at 9600 baud between a PIC and a Raspberry Pi. Both circuits are powered by a 5V wall charger. The distance shouldn't exceed 15cm. They don't currently share a ...
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-1 votes
1 answer
117 views

Why all the other ultrasonic sensors are getting triggered when only one so actually triggered?

I have an ultrasonic sensor, HC SR04, connected to the atmega 8 controller along with an LED for the indication purpose. Let me discribe about my project with some anology. Say I have 20 rooms( ...
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7 votes
1 answer
1k views

Capacitors in MAX 232

Out of curiosity, can I replace the electrolytic capacitors in the circuit with non-polar ceramic capacitors? Will I get the shifting in level? MAX232 datasheet: LINK
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0 answers
322 views

Connect unused inputs/outputs on RS232 line driver/receiver Chip

What is the safest (and reliable) way to deal with unused input/output pins of serial comm. chips like MAX232, ST3232, etc.. So far i'm familiar with these three options: Input and Output Not ...
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2 votes
1 answer
2k views

What TVS diode should use for MAX232 and MAX485, whether uni or Bi-directional?

What TVS diode should use for MAX232 and MAX485 driver, whether to use unidirectional or Bi-directional TVS diode? if any reason why? Also, Please tell me what clamping and standoff voltage to use. ...
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0 votes
1 answer
132 views

Raspberry Pi ver 2.0 UART connection with PC and Xbee

I am trying to connect Raspberry Pi ver 2 with my PC using UART. Connection of my board is Raspi Tx -> Rx RS232toUSB PC Raspi Rx -> Tx RS232toUSB PC Raspi GND -> GND PC Problem I am facing ...
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0 votes
2 answers
622 views

Circuit guidance to output -14V from 12V supply

Good day to all potential problem solvers! I would love some assistance with a particularly tricky circuit. I have an Arduino board and a particularly elusive green/black 128x128 GLCD screen I came ...
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2 answers
443 views

May I use CD4066 instead max 232, to convert rs232 UART(USART) level

As in the title, Is it possible to use the CD4066 as level driver through RS232 and TTL(USART)? If it's possible how this work. Thanks.
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3 votes
1 answer
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MAX232 circuit not working

I am designing a circuit using a MAX232. I have connected Tx and Rx of the MCU to the 11th &...
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-4 votes
2 answers
329 views

LEDs on 3.3V serial and sd card select lines

How would i go about connecting indicator LEDs to the serial lines from my MCU(a Parallax Propeller) to a MAX3232 and the chip select line for a SD card? I want the LEDs to light up when the lines are ...
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2 votes
4 answers
2k views

Electronic switch with negative and positive voltage

I want to use a micro-controller to send data through a max232 that will convert the 0v/5v signals into -12/+12v signals. The problem with this IC is that when there's no signal, it sends a +12v ...
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0 votes
1 answer
5k views

Flashing Hex File to AT89C51

I have a USB to Serial breakout which has CP2102 and MAX232 chips on it. I wrote a program in Keil and generated the Hex File. How do I flash this hex file onto the AT89C51 (which is also another ...
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0 votes
1 answer
841 views

Max232 TX working but Rx not working

I have two PCB which has PIC32 as a Controller and two serial port. I tested the 1st PCB and serial port was working fine. I was able to send and receive data. But ...
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0 votes
1 answer
614 views

xmega serial communication using MAX3232

Hi I am trying to talk to send a character to the PC using the xmega128a1 and the MAX3232 USART to Serial converter chip. Here is my setup and "send char" function below: ...
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2 votes
1 answer
5k views

RX/TX LED for MAX232

I want to use two LEDs to show send and receive on my max232 RS232 to TTL (5v) converter. I have seen this method as the most conventional way to power an LED for max232: I tested it and the LED ...
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0 votes
1 answer
3k views

UART - getting gibberish data from MAX232 with PIC16F877A mcu

I have created a serial communication between my laptop and 16F877A mcu. I have used MAX232EPE IC as level converter also. According to my code If I send a character to the MCU, MCU will return a ...
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2 votes
1 answer
8k views

Max232 giving incorrect values at pins

Background: I'm trying to connect a Compact Logix PLC -> MAX232CPE Maxium chip -> arduino. Currently my PLC does communicate modbus RS232 with a request for data from the arduino. I can see this by ...
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-2 votes
2 answers
696 views

Do we need MAX232/ADM3203 for UART communication with PIC32MX795F512L [closed]

I am trying to communicate UART with PIC32MX795F512L. I am really confused with this thing that we should use MAX232/ADM3202 or pins will directly commnicate. Because in some microcontroller, it is ...
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0 votes
3 answers
681 views

PIC MCU to PC Serial Communication Problem

I was just trying to send continuous stream of letter 'G' from my PIC MCU (PIC18F452) to my laptop. Here is my assembly code that i am using : ...
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1 vote
1 answer
286 views

Questions about an atmega32 serial-bus to RS232 with converter and different logic levels

I have an atmega32 and a FUM DCF-U atomic clock (signal receiver and decoder) of HKW-elektronik. The µ-controller works with 5V and the module on 3.3V. I have to build a converter, because the µ-...
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1 vote
3 answers
10k views

How to program an ATMega328 using a Serial Port without using programmers such as USBasp

I am currently learning electronics. I recently bought an ATMega328 and an USBasp programmer to begin my learning. But I couldn't use the USBasp to program my chip. So I researched on other ways to ...
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1 vote
1 answer
662 views

Additional TX and RX pins for FT232RL Microcontroller Interface

I'm designing a board that needs to be programmable via USB and external TX/RX pins. I decided to use FT232RL ( http://www.sparkfun.com/datasheets/DevTools/Arduino/FTDI%20Basic-v21-5V.pdf ) for the ...
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2 votes
2 answers
1k views

Can I use MAX232 instead of a ICL7660 to make a split power supply?

For an opAmp rails I need positive and negative voltages i.e. Vcc, Vee. I look for a good IC which is commonly used for creating split power from a single power supply. Many recommends ICL7660. I ...
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2 votes
1 answer
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Unpowered MAX232 - input 'leaking' into Vcc

My PC is connected to a MAX232 through a USB-to-serial cable. When everything is powered, there are no issues. However, when I turn off the power, the MAX232's \$V_{cc}\$ has a voltage of -0.5 V (...
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1 vote
1 answer
3k views

Interfacing barcode scanner with arduino using RS232

I want to connect a barcode scanner with Arduino. I used MAX232 to convert the levels. I have taken only 3 pins: 2(RX), 3(TX) and 5(GND) from the DB9 cable and given them to pins of MAX232 as shown in ...
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11 votes
2 answers
3k views

How does the MAX232 double the voltage?

MAX232 Datasheet Hi, I am currently a student so bear with me please! I'm currently using a powering the MAX232 with 5V DC, and when I measure from VCC to lets say, pin 3, I am getting a voltage ...
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-1 votes
3 answers
393 views

MCU cannot communicate with Bluegiga WT12 module

I have the evaluation kit EK-WT12 for Bluegiga WT12 module being controlled by a TI Launchpad. I have used the evaluation kit to communicate to a computer with SPP profile and I have sent and received ...
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1 vote
2 answers
1k views

Speed problems in homemade RS232-to-TTL converter board

I'm still trying to debug this RS232-to-TTL converter board that I've made, shown below. Now I think I've narrowed down the problem to speed: it works fine at 57,600 baud; but it inserts some ...
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7 votes
2 answers
10k views

Problems with homemade RS232-to-TTL converter board based on TI's MAX232

I've designed an RS232-to-TTL converter board based on TI's MAX232 IC that I plan to use to program a few custom Arduino boards that I have. However, I'm having trouble with the board and I'm hoping ...
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1 vote
2 answers
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Voltage level too low for MAX232

I'm trying to connect TI's MAX232 to my Arduino so that I can communicate with my PC. I have connected it exactly as the picture shows: Tx/Rx are not connected because I just wanted to see if I can ...
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