PIC programming

[Søren Knudsen]

> Has anyone of you ever built a dedicated PCB using a Microchip PIC
> microcontroller?

I have,

> The reason is that I'm thinking of building a pretty simple PCB using
> this chip:
> 
> http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en533924
> (or the 18F13K50, which has slightly less memory and is slightly
> cheaper)
> 
> This PCB would present itself as two USB devices, and provide two
> serial
> interfaces. Hence the choice for PIC and not AVR, because Atmel doesn't
> seem to have MCUs with built-in USB support in a PDIP package, and I
> don't see myself soldering an SMD component.
> 
> Not simple serial ports, though, as you might expect; one of them goes
> to some sort of bus system, where there is no master and any connected
> device can start transmitting at any moment. There would also be
> opto-couplers involved.

What that be i2c or SPI?

Both of these protocols can be tough to debug if everything doesn't work as you expect (take it from someone who've done bit banged i2c on a pic16f84... (slave only, mind you)).

> Anyway, the chip is one thing, but it needs to be programmed as well.
> And that's where my question comes in. Basically, I have three choices:
> 1: Build a programmer myself. But the designs you find on the net are
> usually not for 20-pin and/or PIC18 devices.
> 2: Get the PicKit2 programmer for some $35 + shipping + tax.
> 3: Get one of these kits for some $50 + shipping + tax.
> http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=
> 1406&dDocName=en023805
> 
> What would be the best option? It would really be an exercise in low
> cost, but I would also like to retain the option of building and
> programming a couple more and selling them.

For that price, I would definitely choose the debugging option. Seeing as it affords In-Circuit-Debugging, having the possibility of in-curcuit-programming is of less importance.