Bit Banging a Shift-In

SailerMan

I created a Bit-Bang Shift out from the SX28 to the Propeller because the ShiftOut command is too fast for the Propeller using SPIN. It works perfectly. Now I need a Shift IN but for some reason I can't get it to work. Can·someone please give me an example of a·Bit Bang for Shift In Master Clock.


Thanks for any help,
Eric
·

Bongo

for lsb first where the bit you want is on a pin called data and gp2 is a variable


movb····· c,data
rr···········gp2················································· ··;move bit into var


for msb first where the bit you want is on a pin called data and gp2 is a variable


movb····· c,data
rl···········gp2················································· ··;move bit into var



Don't know what you mean "in master clock", and you have set the input levels (ie using schmitt trigger will probably·be not sustainable·) to deal with the 3.3 volt propeller output?


bongo

SailerMan

I Guess I should have said in SX/B not ASM.. Master Clock meaning that the Clock will originate in the SX28. I didn't know if that was needed information. [noparse]:)[/noparse]

Bongo

Oooh, I don't know SX/B, but you must be close if you are shifting bits out.· You did set the pin to input?, and maybe someone else can help with the SX/B



bongo

Sparks-R-Fun

Eric,

I do not have an example I can share right now. However, if you will post what you have that works for shifting out and what you are trying to use for shifting in, I (and hopefully others) can probably offer meaningful suggestions that may help.

In general it looks to me (from a previous oscilloscope posting) that you should:

• Lower the Clock line...
• Pause...
• Raise the Clock line and sample the data,
• Pause...
• Repeat eight times being sure to shift the data into your result variable in the proper direction.

- Sparks