[sdiy] PIC help

[Jason Tribbeck]

Hi,

> 1. What programmer/debugger do you use or recommend?

I use the earlier PICkit2 - although only for programming. Debugging is
done on the fly (as it were).

> 2. How do you decide which PIC chip to use?

Normally with Microchip's parametric search tool (although it is often a
bit of a pain when using it). Plus I have a fairly good knowledge of
what's available.

> 3. Some of the dsPIC chips have a built-in 16-bit DAC...

Unfortunately, I've not used those yet, so can't comment.

> 4. If using an external DAC, is there any advantage...

I've only ever needed a pair of DACs, so again, can't comment. But I did
use an external IIS interface device for it.

> 5. It seems that dsPIC chips don't have enough built-in EEPROM...

I normally hook up an external FRAM device, but I have used EEPROM.
Either in SPI or I2C mode. FRAM is more expensive, but much quicker.

> 6. What do you recommend for an LCD display...

For character displays, they're much of a muchness - all of the ones
I've seen can be driven in 4-bit or 8-bit mode (which means between 6
and 11 I/O pins). You can get I2C and SPI interfaceable LCD displays
which would save on pin count, but they're a bit more expensive. For me,
the key factor is the overall dimensions of the device (so I know
they'll fit the box I've got planned for it).

Although I now find it's more fun to use a graphical display :).

The Lascar GFX-1 is a nice 128x64 display which uses SPI as an interface
(a little small though). Comes with a bezel and a backlight. Only slight
problem is that you can't read the frame buffer so read-modify-write
operations are not possible (unless you use some of your RAM as a second
frame buffer).

So, I now use other displays where you can read the frame buffer -
although you need 13 I/O pins to do so. Latest project has used an RGB
backlight, which is fun (although that's an additional 3 pins for the
backlight colour choice).

Note that the PICs with built-in LCD support are really for those 3
1/2-digit style displays - the pins are used as SEG/COM, and you don't
get that many individual segments to play with (that may have changed -
I last looked about 18 months ago).

Jason Tribbeck
-- 
.sig MIA