Questions tagged [serial-bus]

The process of sending digital data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels.

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78 views

A question about UART communication [closed]

Are there predefined keywords/codes that when sent from a pic to a computer running windows (UART) can elicit certain actions (like show a special pattern or open a picture on the screen) on the ...
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30 views

Serial signal switches from 2V to 3.3v, can I fix it

I have a flight controller that is supposed to transmit a serial signal at ttl levels, in half duplex. The incoming signal appears correctly on my oscope, but the returning signal being transmitted ...
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1answer
58 views

3.3V I2C Logic on 1.8V Device

I have designed a board with the ICM-20789, but am having trouble keeping stable voltage values on the I2C bus. Datasheet I have followed the schematic that was listed inside the datasheet, and that ...
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51 views

MCU based I2C master receiver mode includes transmitter mode or not?

If I am programming an MCU I2C peripheral as a master of I2C bus that will be receiving data from other slaves on the bus. So I will set its direction as 'I2C_Receiver.' But since an I2C slave will ...
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21 views

Pull up resistor selection for LIN bus

What exactly will happen if I use 1.2K ohms at LIN master node pull-up? Why does the LIN protocol spec recommend to use 1K typically?
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1answer
37 views

Chip selection: Serial interfaces

I am narrowing the selection of an uC for my project and currently reading the datasheets. One contender is Microchips 'ATSAMC21*' series. Using the parametric selection tool I get following ...
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5answers
1k views

How to end sending data over I2C by Slave or Master?

Let us say a Slave or Master is sending multiple bytes to the receiver on I2C bus and the number of bytes is not defined before hand. So then how will the sender tell the receiver that it has no more ...
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2answers
128 views

I2C data sampling is done at clock edge or level

I am trying to understand I2C data bus from this document. It explains the START-SLAVEADRESS-R/W-ACK-DATA.. as the master-slave take turns to get hold of the shared bus for mutual communication. One ...
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2answers
52 views

Data send only in MCU based I2C Slave

I want to know that is it possible that a Slave I2C device which is a 32-bit MCU, for example STM32F407, I write its I2C data send function and send data through it after every 1 sec? I am asking this ...
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1answer
76 views

MCU to MCU I2C communication

I have 2 MCUs and I want to connect them together over I2C bus. MCU1 will be Master while MCU2 will be Slave. Only these 2 MCUs are on the bus. This configuration is fixed and I cannot change it. ...
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55 views

Are there software to simulate timing diagrams for serial communication circuits?

For the purpose of learning(not necessarily designing), I want to simulate basic serial communication ICs such as MAX485 or MAX232. An example circuit can be as follows: Now instead of building this ...
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43 views

DRV8889 SPI Commands

I've been having some issues diagnosing the relationship between writing to the registers through SPI commands and stepping the motors. That is, it seems like when I write SPI_STEP=1 (and STEP=1) to ...
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Issue with SPI read and SPI speed

I want to read out the content of a NAND Flash and I decided to do this via SPI. I have a Bus Pirate to communicate with it. I modified a Python script to read out the content and it works to a ...
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2answers
143 views

Reverse-engineering RS485/Mechatrolink-II front-end design

I'm trying to reverse-engineer Mechatrolink-II front-end circuitry. Its physical layer is simple RS485 (with isolation transformer) running at ~10Mbps. Here is the schematic I obtained from the PCB of ...
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1answer
34 views

Comparator with hysteresis for bus-powered communication

I have a circuit that, supposedly, converts a current-modulation signal to a digital signal. This is basically the receiver end of a bus-powered, bi-directional serial communication device (master). ...
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1answer
259 views

RS422 and RS485; full-duplex or half-duplex?

I have extensively used RS232 transceivers in many projects and have fairly good understanding of UART communication using RS232 transceivers. MAX232 and MAX3232. Now I have to build my understanding ...
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3answers
97 views

What is the difference between a multiplexed bus and a multi-master bus

The jargon of terms in bus architecture literature is half the difficulty in understanding it. At some places the term 'multiplexed' bus is used while at some other places 'multi-master' bus is used. ...
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2answers
80 views

Lack of 'determinism' in Ethernet bus

While reading this website, I found out tha there is lack of 'determinism' in the Ethernet network bus as compared to some other buses like 1553. What I understand is that Ethernet is a single master ...
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26 views

CAN Transciever kbps to Hz at TXD Pin

I am new to the CAN Bus and have designed an application example. The Transceiver I have chosen is TJA1044Gx. The transceiver data sheet says : I want to know if I have only Transceiver, Analog ...
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1answer
98 views

How would I place CAN termination resistors in a 3 ended configuration?

I have a project for which I have one central circuit board which has a can node on it, this central circuit board has three connectors on each of which a node could or could not be plugged in with a ...
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2answers
422 views

Maximum Switching Speed Chained 74HC595

I'm planning to use a set of daisy chained 74HC595s to control a set of 108 mosfets, 3 of them are geographically in the same area (couple of mm apart) and for the sake of modularity should each use ...
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2answers
193 views

RS485 vs RS232 similarity vs differences

I have used UART RS232 communication between MCUs extensively. Now I need to interface my STM32F407 MCU over RS485 bus with with devices. I have understood few things about RS485 but not-clear about ...
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3answers
1k views

Direct connection of UART serial port to USB type-C

in my project I have a USB type-C 3.1 2nd Generation (24 pins), which should provide 5V to a charge battery/battery system. In addition, there is a uC powered at 3,3V where the maximum voltage on GPIO ...
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2answers
86 views

How to select the most appropriate (serial) bus for controller?

In the context of a robotic project where different 'payloads' and/or robotics arms (end-deflector) should be mated mechanically with power, data and control connections support, I would like to ...
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1answer
221 views

What does it mean when i2c_smbus_read_byte() returns 0

i2c_smbus_read_byte() returns a negative value when there is an error in reading data. But what if it returns 0? Following is the code from adt7316-i2c driver ...
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135 views

How does this serial input DAC work?

This is the datasheet for 6379A: datasheet I looked at the timing charts, but I’m still having trouble figuring out how the IC treats the serial input. Apparently, SI is sampled at positive clock ...
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1answer
203 views

Daisy chaining I2C modules using CAT5 and P82B715

I'm planning to connect several modules over I2C with distances between modules ranging 30-180 cm. I understand that in order to avoid the degradation of the signal due to the capacity of the ...
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1answer
234 views

MAX485 suddenly drawing too much current and output voltage levels are not right

I have two PCB that I designed and they are made by a PCB manufacturer (so they are identical). They use a MAX485CSA to communicate but suddenly one of them is drawing too much current, on a normal ...
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3answers
942 views

How to find out whether serial standard is RS232 or TTL when stated as “serial(RS232/TTL)”

I am recently moving from C programming into automation engineering. I have learned about RS232 and TTL standards, and I understand that they are based on the same concept of serial communication, ...
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2answers
2k views

Switching RS-485 bus

As shown in the graph, I'm trying to use mcu-controlled switches to turn a segment of rs-485 bus on or off (so that only one segment is on at a time). I was considering analog switches but I'm not ...
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1answer
407 views

ESP32 AND CP2102 Serial data reading issue

I have a PCB on which i am taking a 5v - 1A DC power supply , and again providing 3.3v to ESP32 through AMS-1117 3.3v. Basically things are not working on when i solder the esp32 on my pcb but things ...
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3answers
92 views

Data transmission over up to 100 ft

I need to transmit data (less than 5Mbps) point-to-point over 100 ft. I prefer not using Ethernet due to the complexity. I can use low-scale FPGAs or similar chips if needed for functions like error ...
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2answers
277 views

2-wire MPU interface / 2-wire Serial Control Interface?

While reading datasheet of an audio codec IC, I got confused over the term "2-wire MPU serial interface". Is that just another term for I2C (just like TWI or TWSI) and they are fully compatible? And ...
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1answer
145 views

Avoid reboot of USB serial device when another USB device is inserted [closed]

EDIT 7/7/2018: Can't add an answer because this question is closed however there is an answer here. It is not a problem related to Windows only. The reset is caused by hardware behaviour, the ...
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1answer
79 views

Suitable 12VDC Communication protocol for untwisted unshielded long-ish wire length?

What would be a reliable and simple tranceiver interface/protocol for board to board serial communication at about 100ft. [9600bps or lower is fine.] The two-lead communication wiring cannot be ...
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2answers
73 views

Quantifying Eye Diagram for high-speed SERDES channel

I need help quantifying Eye Diagram. I have to quantify Eye Diagram at the end of my Thesis for my Serial Link channel. Viewing an Eye Diagram, I can say probably whether it is bad or good. But for ...
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2answers
397 views

One master to 32 slave pic microcontroller communication, bitbang

I'm trying to communicate with 32 microcontrollers (PIC 12f675). These are used to control 32 DC motors and 2 sensor for each PIC. So only two pins are left to communicate with master device. I want ...
2
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1answer
861 views

I2C bus extender

I am working on a project which requires a long I2C bus which can be long as 200m or more.I searched on the internet and found a chip nxp PCA9600.I would like to know is there any alternate for this ...
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2answers
366 views

Reliability of Serial IO Expander like MCP23S17

Background: I am doing a re-design of an existing system moving from HC11 base with memory mapped I/O to an ARM Cortex-M3 with serial SPI/I2C I/O (opto-isolated inputs and relay outputs). I/O access ...
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2answers
195 views

Serial communication protocol [closed]

I want to learn about the raw serial communication protocol (The one that uses the Rx and Tx pins of a microcontroller). I want to be able to send bits of data without using a microcontroller. How ...
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0answers
84 views

12 bit asyncronous USART using pic (rx)

I need to implement an asynchronous receiver USART. The length of the frame is 12 bits. I looked into implementing this with a pic 16F1455 but it only supports 8-9 bits: "Programmable 8-bit or 9-bit ...
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4answers
3k views

Decoding message data on this CAN bus

I am working with the CAN bus and need some help with decoding message data. Here is a sample of the data that I'm seeing on the CAN bus. ...
2
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1answer
940 views

Where is the benefit in SQI parallel interface over SPI? Parallel vs. serial

Microchip is offering a number of serial SRAM chips with a communication protocol called SQI which is similar to SPI but with 4 parallel bits written at each CLK toggle. If you can spend the extra 3 ...
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3answers
976 views

Is RS-485 a suitable physical layer for Atmega chips in a home monitoring situation?

I am intending to build some Atmega based home monitoring chips. I want to monitor temperature, humidity, and current levels. Current level monitoring would be done with an inductive pickup on AC ...
2
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2answers
717 views

Why would credit card reader over audio jack not work on some devices?

This isn't a troubleshooting question, it's purely to satisfy my curiosity... MagTek makes a product called the uDynamo credit card reader that uses the audio channel on android devices as a ...
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2answers
321 views

usb to rs232 serial communication

I have to configure my rs232 to device(transmitter) using usb to serial communication. I have tried with usb to rs232 cable and connect the transmitter 6 pins to the db9 connector but it did not work. ...
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3answers
535 views

LCD interfacing Issues: Embedded Systems

Hobbyist tend to use parallel communication for interfacing with an LCD and all the libraries are for a specific type of microcontroller (Arduino or AVR) or LCD. But, for a design engineer, it is ...
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1answer
993 views

FT232RL USB to serial : 5V or 3.3V set by jumper

I've just bought a cheap FT232RL USB To serial adapter (EAN: 0680004529143). It does not come with a manual and the short description simply mention: USB power supply, can choose 5V or 3.3V ,set by ...
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1answer
313 views

Tool or method to listen to a custom RS485 bus traffic

How do I listen to a CFLink bus for data? The said bus was implemented on top of RS485. I've tried hooking it up using an RS485 to serial adapter and RealTerm but I've got nothing returned even though ...
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4answers
322 views

Device discovery on simple bus

I am currently facing following problem: there is a system, which consist of one master device and some number of slave devices (all those devices have tiny MCUs). They communicate with some custom ...