Arduino clone with dual MCU support

HI All,

I ve just finished constructing my new standalone arduino based system.

I thought I d share a photo for your comments, suggestions.

Main features:

Dual atmega 32u4 or atmega1284p support (Either chip can be soldered on the pcb on separate footprints. Note second MCU not shown in photo is on the other side of PCB)

Onboard RS232 interface
Onboard RS485 interface
Onboard switching power supply with 10-24V AC or 12-30V DC supply (supplies 12v,5v and 3.3V)
Onboard Serial EEPROM (2 ICs)
Onboard relay driver along with 6 power relays (mains)
Onboard socket for nrf24 radio comms
I2C temperature sensor and I2C interface expansion available
Number of expansion headers available (8 bit digital, LEDs, I2C, etc)

All the above are accommodated in a double sided PCB measuring 10x8cm designed to also fit in a DIN rail mounted BOX if required.

See photos , more to follow

More…

Nice job.

How do the two CPUs interact?

How do the two CPUs interact?

They dont! In fact they dont even coexist!

I have only provided space, that is the pcb foot print, for an alternative CPU for more demanding applications.
Only one CPU can be present at a time either the atmega32u4 one one side or the atmega1084p on the other side of the pcb. They share most components i.e crystal etc apart from the decoupling caps that each one cpu has its own .

Ah I see.

And the opposite side…

skyBoard Side B.jpg

I have a couple of dual MCU boards also, not as much extra circuitry, just an RS232 buffer that can connected via header jumpers. Use offboard USB/Serial adapter of your choice.
Schematics available here
http://www.crossroadsfencing.com/BobuinoRev17/
Dual ATMega328P Board
40 IO pins. Headers to connect USB/Serial adapter, ICSP, jumpers to connect MAX232 for Serial.
Add some jumper wires for chip-to-chip SPI, I2C, or UART-UART comm's.

Dual ATMega1284P Board
64 IO pins. Headers to connect USB/Serial adapter, ICSP, jumpers to connect MAX232 for Serial.
Add some jumper wires for chip-to-chip SPI, I2C, or UART-UART comm's.

Nice!
So is there any connection between the two CPU's ?

Picture showing the PCB in a Din rail mountable BOX with top cover open:

  1. Front side showing DC supply and RS485 screw terminals on the left together with easy access to USB and ICSP header and the 8 bit i/0 screw terminals on the right

in din rail box2.jpg

  1. Other side showing the screw terminals for connection to 120-230V AC upto to 10A :

In Din rail box1.jpg

Planning to build a number of these to use as part of a home automation system…

Watcher:
Nice!
So is there any connection between the two CPU's ?

See post #3

See post #3

I was referring to the Crossroads system.. Not my own!

Oops, didn’t even notice it was you :slight_smile:

@Watcher, your board and enclosure look good they have an industrial look.

@Watcher, your board and enclosure look good they have an industrial look.

Thanks! The enclosure is from...ebay. As for the pcb, it took me 4 failed atempts to get everything working. At first i started with a pcb design with an arduino micro plugged in on female pin headers. By the third attempt i decided to go for stand alone system and got rid of the micro. That design was ok apart from the fact that i swapped the sda and scl lines! At the final attempt I also switched to smt technology which ment I could fit much more components on the same size of pcb. Having power relays also meant that i had to go for 2oz copper tracks in order to meet the current requirement which increased the pcb cost...

The uCs on my boards can be connected however one desires - analog/digital pin to analog/digital pin, I2C, SPI, Serial, RS232 out to a device from uC1 and back from a RS232 device to uC2, connect USB/Serial adapter to both and go to different USB ports, etc. Nothing is preconnected to allow max user flexibility.