2011 THT VOTER Bootloader Woes

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1

Hi,

Recently I got some of the VOTER THT PCBs made and I started populating them.

I tested each part just before I soldered them except the Xtals, ICs, ferrite beads and very small value capacitors.

I also had to find equivalents for a lot of the parts and I checked the datasheets for them so they should all work but I may have to double check though they should not prevent the bootloader from working. (can provide a list if needed)

Once done I cleaned the PCB with alcohol and began the software side.

I used mplabV8_66 and mplabc30-v3_31 to upload the bootloader I also included the .cof file but did not change the IP address.

Original PikKit3 used.

I also removed JP7 for before programming..

The terminal gave me program/verify complete.

Placing JP7 back and power cycling the PCB and… no fast LED indication… however there’s a constant current draw of about 65mA.

however the PCB is dark….

My first thought was perhaps the bootloader checks the 9.6Mhz crystal and the one I’m using is not accurate enough.

So I changed it and rinse and repeat but still no joy.

The PPM should be ok just the load capacitors are 20pf.. so maybe there’s some sway but I can’t really find a way to test the crystals so much sadness…

So I decided to ask: Could the problem be the crystal?
The bootloader can be programmed but I think there’s a check preventing the PIC from getting ready for the firmware.
If the crystal is the issue could I some how change the .cof to have a bit more leeway?
I won’t be using this for simulcasting just experimenting and maybe a repeater setup or two if they work well enough…

Anyway any help or suggestions would be greatly appreciated.

9.6Mhz Crystals used:

I could not get the correct ones so I kind of had to gently bend these legs and used the labled 20pf SMD caps for them.. so it didi’nt look too bad but was still not ideal…

2

Let’s start with simple…

Have you confirmed you have Vcc and Gnd on all the ICs?

Is LED1 installed with the correct polarity, and/or have you put a scope on U8 pin 21 to see if there is activity?

Lee

3

You have probably figured it out by now, but the crystals are not the problem for booting. People have clocked it at 10MHZ, although that broke other things, but it still booted.

4

You might get it to boot with 10MHz, but it won’t work.

There is a specific reason for using 9.6MHz for the oscillator. It has to do with how the clock gets divided down, and the ISRs are called to allow for audio to be encoded at 8kHz PCM.

Sure, you could change the code to make the PIC take a 10MHz clock, but your audio won’t work.

If it were that easy to use a 10MHz clock, it would have been done long ago. It should would make simulcast a lot easier…

Plus, the bootloader is a binary blob, and expects 9.6MHz to start up. Unless you hack the bootloader firmware, it won’t boot with 10MHz if the bootloader exists (I know, I’ve tried).

Lee