How Pssible adding more I/O Ports to Arduino Due

[ahmed_shoihy]

Hallo,

Wie kann man mehr Ein/Ausgänge bei Arduino DUE Addieren ?
Falls nicht gibt andere Module. die eine Erweiterung an I/O anbietet?

Danke im voraus

[gilshultz]

How many do you want, 1, 8,16,23 etc? There are a lot of choices and chips that will do what you want. Do you need each port to be input, output, both, A/D? What interface do you want to use, you have two I2C and SPI. Which version of the DUE do you have? Simple shift registers could do what you want, there are also some more involved chips such as the PCF8574 etc. More information so we can better answer your question.

[ahmed_shoihy]

Hello,

Thanks for your replyment

For my Project I need to have:

1. Up to 60 digital Outputs to intiate 60 Relais for Short circuit testing with 20 Amp and up to 30 Volt DC.

2. Around Min. 25 Analog Input Signals for messure Current and Volt and might need more.

I don't have any Modules i just searching for the best choce for doing this project so i am still in the research fase.

I found Due Module has up to 54 which is the bigest one and i thought that i could modify it and add more ports on it.

Could you help me to find the sutable combination for this Project

Thanks alot

Ahmed

[groundFungus]

I like the MCP23008 (8 bit) and MCP23017 (16 bit) I2C expanders for more digital GPIO pins. Up to 128 additional GPIO pins with 8 MCP23017 chips.

[gilshultz]

For the analog you can use analog multiplexers and or external A/D converters. Your choice has a lot to do with the resolution and speed you will need. There is a part MAX4820 which will directly drive 8 relays and has either a parallel or in your case a serial interface.

[ahmed_shoihy]

Thanks for your replying,

For intiating 55 Digital Relay Outputs i will use:

• 4 Chips MCP23017 or 3*MCP23017 & MCP23008(8-bit)
• Trnasistor Drive ULN2003A for getting 12 Volt from the MCP
• Then will directly connect them to relays

For 55 Analogue Signals (Volt and amp measure)

• 74HC4067 16 Analog
• ADG732 32 Analog
• And the rest will get it from Arduino

For Can-Bus will use:

• Arduino-mkr-can-shield

Now i have 2 qustions
1- is this structure applicable?
2- should i Use Arduino Mega or UNO for this Structure

Thanks for help

[gilshultz]

Start with either a Nano or Uno, they should be able to do what you want. If not then the Mega will give you more memory. For can I used teh MCP2515 module with Cory Booker's CAN library "mcp_can.h". I am going to take a SWAG and assume you do not have much experience with CAN. A few key points. There must be two units or more on the bus as the message sent must be acknowledged. Termination is required on the physical ends of the bus 2 x 120 Ohm resistors. The modules I suggested you just add a jumper. The library has a send and receive .ino pieces of code, they work. Check crystals and adjust the code accordingly. Also start at maybe 125K on the baud, you can always go faster later. Let us know how you do.

[ahmed_shoihy]

Thanks for your Answer it was really helpful.

I have two question:

1- what if i used Shift register to reduce the Microcontroller chips. is that safe as i need the 55 relays for short circuit test.

2- For measuring the current with more accuracy i think i need to connect the Multiplexer with current sense IC instead shunt resistance. Which one could be possible for connecting all of these Analoge Pins .

Great Thanks
Ahmed

[gilshultz]

The shift registers would probably be the most economical choice. I would use ULN2803 for the relay drivers, that will take one less chip. The A/D should work great. Your choice for the processor should be first based on the outputs you need, once you have that the next thing will be the amount of memory. From w2hat I understand you have the SPI committed to the CAN, the I2C committed to the outputs while your analog converters will use mainly digital outputs. Unused analog I/O can be used as digital outputs but they have no internal pull up. Sharing the digital pins on the analog multiplexers you have enough pins with the UNO and some to spare. If this is a one up and price is not critical go with the Mega but the UNO should be able to do it as well. ahmed_shoihy information is right on.