SPI byref calls

[YahooArchive]

I already have 220 Ohm pull up resistors and 10k Ohm pull down
resistors on all three of the pins. Should I try a higher value for
the pull up? I'll try different resistors and different pins to see if
I can get any results. Although I already tried making the pins go
high and low with the IO command and they worked fine.

[YahooArchive]

220 ohm is too small of a pullup. The IOs are rated at 4mA. 4mA
times 220 ohms is about 1V, so its probably not pulling that line much
below 2V

1K would be a better value

Not much reason to have a 10K pulldown as well, I'd remove those, its
just contributing to global warming

[YahooArchive]

I had a little bit of luck this morning. I took out the pull downs and
changed the pull ups to 1k and now I'm seeing a clock and data being
sent out. The problem is that the signals are only 10mv which I don't
think is high enough for the ARM to read. Looks like I need to do a
bit more tuning.

[YahooArchive]

I think this just might have been a pin issue. I switched the pins to;

SPIIN(1, 0, 3, -1, 0, 0, "", 50, INlist)

and now I'm getting a well formed 3.3v clock and the CS pin is going
high then low like its suppose to. Except now my ADC isn't outputting
anything. This is very frustrating.

[YahooArchive]

SUCCESS!!!!!! Had a bit of a grounding issue with the AD but I got it
working. Well sort of anyway, I still need to figure out the exact
protocol. Here's the code I used to get just to get an error message
form the AD for future people that might need help.


------------------------------------------------------------------------
'Program to capture data from an external A/D converter

#include <SPI.bas>

DIM INlist(5) As String

const CLKpin = 3 'SPI clock(connects to uM-FPU SCLK/SCL pin)
const Outpin = -1 'SPI data out (connects to uM-FPU SIN/SDA pin)
const INpin = 0 'SPI data in (connects to uM-FPU SOUT pin)
const CSpin = 1 'SPI CS (connects to uM-FPU CS pin)

SPIIN(1, 0, 3, -1, 0, 0, "", 5, INlist)
print INlist(0)
print INlist(1)
print INlist(2)
print INlist(3)
print INlist(4)
print INlist(5)

----------------------------------------------------------------------