I’m creating a project using the Cerb40 with the gadgeteer framework. My problem is that I need to use 3 different UART ports. When creating a project in Gadgeteer, the FEZ Cerberus must be selected to use this processor. However, the FEZ Cerberus only has 2 U socket ports. This allows me to easily use two different sets of UART ports by plugging in directly to the approapriate pins on the Cerb40, but I’m not quite sure how to go about obtaining a third port.
If you check the schematic for the board, you will see that there is another UART’s pins available on socket 3, but not in the U socket configuration. But, this still might not help. This port might not be available in the firmware.
You would have to check the current open source firmware source to see any of the additional UARTs on the STM32F405 chip have been implemented. If not, you would have to add the support, and build you own firmware.
I suspect, unless you are prepared for a lot of additional work, you will not have three UARTs available.
Only two ports have been placed on the headers. You could solder wires to the processor chip to get electrical access to the other UARTs, but there might still the issue of firmware.
The processor chips have limited memory, and implementing UARTs requires transmit and receive buffers. I suspect GHI made a design decision to limit the number of UARTs supported to conserve memory.
The chip has six UARTs, but GHI has been careful to specify that they only support two.
@ Justin - I’m new to microprocessors and originally started this project on a FEZ Spider. It was easy for prototyping and worked quickly. We then started selling the product, so it made sense to swap to the Cerb40 because code ported over very easily, it’s much cheaper and much more compact. Unfortunately that was back when only 2 UART ports were required. I need a third now.
I haven’t yet put the time in to figure out how to convert off of gadgeteer, although from the sounds of this post it looks like it might be time!