Back Where I Started

With regard to the DRO PCB anyway, just this time it is using an ARM (LPC11U14 specifically) on an LCPXpresso board that I had floating round for another project.

As you can see, the code is ported over, well the OLED driving stuff anyway, and all is up and running. Just the TFT and LED displays to do, then I can attach the gauge boards and get it running. That's where it all started to go wrong with the PIC based PCB. The LPC stuff is much more solid. I've not seen the OLED problems I saw with the PIC, and it's the same code, so there was something odd going on with the PIC. The LPCXpresso board has a JTAG debugger on one end too, so the DRO has it's own debugger. That works perfectly too, I've managed to get a stack trace from it when I made  porting error, and it was easily debuggable. All in all, much better.

The only thing is that the LPCXpresso board is much more expensive than a PIC chip, but I can probably make my own target board later and take the LPCXpresso board off the DRO. Maybe. I may just leave it there, it'll make programming easier later on.

Change of DRO Direction

 I've spent a lot of time recently trying to get the PIC16F18875 working as the main controller on the DRO. It's sort of working but there's problems. Whenever I make a simple code change (something like changing a /1000 to a /10) the code sometimes just fails to run. This would be fine, as it's probably a bug, well maybe, but as the Microchip debugger also doesn't seem to work, it's all a bit of a disaster. Looking on the web it seems this is a fairly common experience. It's a shame as I've used PICs a lot in the past and they were useful little devices. Anyway, I've decided to ditch the PIC and try something else. At the moment he plan is to use an LPC1114 ARM based device. This has the added advantage of more flash (32K), similar clock speed and lots of GPIO. Unfortunately it is a 3V3 device and that means I will have to deal with level shifting and add a regulator.  Anyway that's all OK, just a bit more complexity and if it works I can lay out a mostly 3V3 PCB with the LPC on it.

The other thing about the LPC chips is that they don't come in any DIP packages. Not that are available to buy anyway. So I have tried to mill a QFP48 footprint that is one of those used by the LPC1114. Once I used a 0.1mm cutter and a shallow depth of cut, I managed this:

It's not perfect, there's a bit of copper that hasn't been milled away. I think I may be able to sort that with either a second milling or slightly more depth. Anyway, it looks to be possible, so that's the plan.
Those pads are 0.5mm between centres, by the way.