The MiniMig PIC update issue thread

[yaqube]

Try this:

Before you click "CheckPIC" or "Write Flash" button press and HOLD the "PGM RESET" switch. Then click the desired button and then release "PGM RESET" switch.

Please tell me if this works for you.

[yaqube]

If we assume that at least one of the PIC's you have got is programmed with valid bootloader (I hope you have tried both with my suggestions) the serial connection might be faulty.

To verify this please remove the PIC from its socket, connect pin 17 and 18, power on the board without the PIC, run terminal program and check if you get remote echo of typed characters.

[yaqube]

odin22 wrote:

To verify this please remove the PIC from its socket, connect pin 17 and 18, power on the board without the PIC, run terminal program and check if you get remote echo of typed characters.

Ok, I might need some more info here. Do I connect the socket holes on the board where pin 17 and 18 were supposed to go? And with what - a paperclip or piece of wire? Won't that short circuit it?

Yes, you should connect socket holes for pin 17 and 18 together. I hope you know the order how the pin are numbered. Connect them with thin wire with removed insulation at both ends, it would be great if you could cover the ends with tin (I guess you have said you can solder). Avoid paper clip since it will destroy the socket.

That way you will be able to verify if the components on the Minimig board responsible for bi-directional serial communication are not broken.

[yaqube]

Windows settings of serial port baud rate does not matter, Tiny Bootloader app overrides these settings. Besides Tiny Bootloader programmed into the PIC works only with 115200 bps using 20 MHz crystal oscillator. Some (the cheapest) USB to RS232 converters are not reliable when working with 115200 bps speed.

Can you see in Hyper Terminal (set rate to 115200, 8N1, no flow control) any messages sent by Minimig after powering it up?

[yaqube]

You should see the following message:

Minimig Controller
by Dennis van Weeren

Try to change the serial port speed in Hyper Terminal to 57600 or lower, it seems that your PIC is operating with different baud rate (although you should see more strange characters than only these two - while Minimig is booting up it sends a lot of characters on its serial port, had you put an SD-Card with minimig1.bin file?). Please also check what is written on the crystal oscillator next to the PIC socket. Is it 20 MHz?

[yaqube]

I have made a small experiment: set my serial port speed to 460800 and I get the "Ç" character as the first after reset. It means that the Minimig transmits 4 times slower than it should.

Maybe you have 4.43MHz crystal oscillator connected to the PIC or the 20MHz one is an overtone oscillator and in your Minimig it oscillate at its fundamantal frequency.

The PIC has programmable bits for oscillator configuration, if they are not programmed to HS mode the oscillator may not be able to operate at its rated frequency. These bits can only be programmed in external programmer.