can i talk to multiple arduinos at the same time with another arduino, in a serial format?

Question

Hello all,

I am trying to talk to multiple (say 4) microcontrollers (Arduinos) at the same time. I was wondering if i can setup a serial connection, with a selection line that can detect the neighbor Arduino and enable the corresponding pin to start the serial communication between the two. something like this:

Robert Peter Oakes · Accepted Answer

There are several options and without complex switching, the standard TTL pins on D0 and D1 are off the table, at least for direct use

I2C is an option, each arduino would have its own address assigned and they could all talk to each other or have one assigned as a master and act as a relay

SPI could work but as it is based on using chip selects, as the number of nodes increases, the complexity goes up with it (Rapidly)

with the addition of a simple RS232 (TTL) to RS485 (Differential Drive) chip on each arduino, you could implement a custom protocol or an old but still very popular industrial control protocol called MODBUS https://en.wikipedia.org/wiki/Modbus, this is still a defacto standard with many PLCs and other control devices, has been around since 1979 and there are drivers for most microcontrollers including many for the arduino

Modbus would allow upto 127 devices to be attached onto a single RS485 serial link, I am actually currently working on projects using this protocol and will be integrating many different types of devices as I go, All educational purposes though, not for a specefic product

Hope this helps

bobcroft · Answer

Karim, further to Peter's reply I have done something similar to what you want to do using RS485 modules bought cheaply from China / Hong Kong. (Have a look on www.yourduino.com for modules and very useful information) These modules contain the necessary parts to correctly terminate the differential line drivers. One of the advantages of RS485 is that it can be used to link Arduino's 100's of meter's apart. These modules are easily connected to the Arduino's using either the hardware serial ports or the software ports using softSerial. There is an Arduino library called EasyTransfer, by using this library you can transmit your data and the address of the recipient Arduino. All Arduino's on the system receive the transmitted data but only the one with the matching address responds to it. The RS485 bus is bi-directional so each Arduino can both send and receive data. You can use your own custom protocol as to what information you send. MODBUS is well supported but was much more than I needed. Hope this helps

Former Member · Answer

it is quite of a simple concept: you have multiple units that you can mix and match to pave the way for an assistive surface for tactile sensing, which is modular. so the units may be added/removed from the swarm or replaced with another one, with no difference in the performance of the system. as a result each unit (node) consists of a microcontroller that processes the sensors' input, and transfers those values, along with its own ID, to the one directly connected, and ultimately to a base unit. I am hoping this clarifies...hence the sensors are needed, as well as all 6 serial communication with other units. would it be possible for me to make 6 soft serials out of the pins of Arduino Micro? 6 RX, 6 TX, 1 VCC and 1 GND?

Robert Peter Oakes · Answer

Use a pair of ESP8266 as wireless transceivers, there probably cheaper that any other WIFI shield on the market and really easy to use.

can i talk to multiple arduinos at the same time with another arduino, in a serial format?

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