Mcp3204 adc

Greg LaPolla

I am trying to convert the mcp3208 object from obex to work on the mcp3204. I don't have a real good understanding of assembly, and I think I am making more difficult because of it.

I have made some changes, but the problem seems to lie in this bit of code:

cloop                   shr     t2,#1           wc      'if channel disabled, skip
        if_nc           jmp     #skip

                        test    t2,#4           wc      'channel enabled, get single/diff mode
                        muxnc   command,#$04
                        mov     stream,command

                        or      outa,smask              'CS high
                        or      dira,dmask              'make DIN/DOUT output
                        mov     bits,#20                'ready 18 bits (cs+1+diff+ch+1+0+data[noparse][[/noparse]12])

the

test t2,#4 wc
muxnc command,#$04

seems to be the culprit.

In the mcp3208 they are

test t2,#$80 wc
muxnc command,#$08

I looked at the mcp3202 driver and they are
test t2,#2 wc
muxnc command,#%0100


I am not sure how to proceed. I have already read potatoheads beginning assembly and the assembly book from deSIlva and I still can't figure it out.

Thanks in advance


Greg

tae2010

Check out my thread, http://forums.parallax.com/showthread.php?p=904652. I setup a 3202 with a piece of code I found on OBEX also. Hope it helps, its much simpler to follow than the assembly code version.

StefanL38

Hi Greg,

you can give the ADC Input Driver object from the obex a quick try if it works for you

I haven't tested this object myself but the author describes that

"Known supported ADCs are:
MCP3208, MCP3204, MCP3202, MCP3201, MCP3008, MCP3004, MCP3002, and MCP3001"

So I assume the author has tested the devices mentioned above as working

best regards

Stefan

Post Edited (StefanL38) : 6/20/2010 10:13:03 AM GMT

mynet43

Hi Greg,

I have an ADC driver in the OBX called MCP3208_fast.

I believe it should work with the 3204 without changes. It has the same calling sequence as Chip's routine, but it only accesses one port at a time, the one you ask for.

So if you use it with ports 1,2,3 or 4 it should work fine.

Let me know if you have any questions.

Jim

JD

Thanks Stefan... this was a nice help to use a MCP3204 for the Joystick. It's for a remote control Stingray Project I'm doing. Im going to use the other two channels to check for voltage on the battery pack.