Just having trouble getting the firmware to load on my board.
I want to verify that I have the DB9 wired correctly.
I am wiring the DB9 directly to the board, instead of going through the headphone jack from Mauser.
I know Tx and Rx get connected to pins 2 and 3, but which goes to which?
There are pads labeled Tx and Rx adjacent the serial plug location on the PCB. I would connect directly to those.
The connection to the DB9 are:
- Tx -> DB9 pin 2
- Rx - DB9 pin 3
- Gnd - DB9 pin 5
You can get this info directly by comparing the MAX232 connections on the GPIO board to those on the V3 main board.
I've been doing the majority of my attempts at burning firmware with the Tx and Rx wired wrong. Maybe I'll have more luck now
Another quick question. Does the headphone jack from Mauser protrude across the edge of the PCB? I.e. Can it be soldered to the board without drilling a hole in the case?
The serial plug is designed to be flush with the end of the PCB. So you don't have to drill a hole in the end plate for it if you are going to pull the end plate to use the serial port.
Another alternative is to bring the serial comms out the Ampseal connector, and wire them to either a DB9, or a headphone plug (or some other 3+ pin connector, if you like). This is described here: http://www.msgpio.com/manuals/mshift/assembly.html in step A.8.1 and A.8.2
In some cases one might use up all of the pins in the ampseal so in those cases it is better to not bring the serial out through the ampseal correct? I haven't looked at how many spare wires there are in the ampseal so I don't know the answer yet.
All of the 25 I/O circuits are assigned a particular pin on the 37 pin Ampseal connector, with enough left over for the power, grounds, CAN, and serial connections (which are also assigned to particular pins). The serial pins are set aside regardless of whether you use them or not (however, some people might choose to run the bootloader connection through one of the serial pins, for example, so they can load code without having to open the case).