Andy K / Mbed 2 deprecated AD9951TEST

Attempt to read the AD9951 DSP serial output via SSP and \"IRQ driven bit-reading\".

main.cpp@0:e45bbd4486df, 2011-01-18 (annotated)

Committer:
AjK
Date:
Tue Jan 18 01:27:57 2011 +0000
Revision:
0:e45bbd4486df
0.1 A test failure case!

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AjK 0:e45bbd4486df 1
AjK 0:e45bbd4486df 2 #include "mbed.h"
AjK 0:e45bbd4486df 3 #include "iomacros.h"
AjK 0:e45bbd4486df 4
AjK 0:e45bbd4486df 5 DigitalOut led1(LED1);
AjK 0:e45bbd4486df 6 Serial pc(USBTX, USBRX);
AjK 0:e45bbd4486df 7
AjK 0:e45bbd4486df 8 // The two main functions, call one or the other
AjK 0:e45bbd4486df 9 // depending on P20, one Mbed or the other.
AjK 0:e45bbd4486df 10 void tx(Serial *, DigitalOut *);
AjK 0:e45bbd4486df 11 void rx(Serial *, DigitalOut *);
AjK 0:e45bbd4486df 12
AjK 0:e45bbd4486df 13 int main() {
AjK 0:e45bbd4486df 14
AjK 0:e45bbd4486df 15 p20_AS_INPUT;
AjK 0:e45bbd4486df 16 p20_MODE(PIN_PULLUP);
AjK 0:e45bbd4486df 17
AjK 0:e45bbd4486df 18 pc.baud(115200);
AjK 0:e45bbd4486df 19
AjK 0:e45bbd4486df 20 if (p20_IS_SET) tx(&pc, &led1); // This is the sending Mbed that creates the waveforms
AjK 0:e45bbd4486df 21 else rx(&pc, &led1); // This is the receiving Mbed that tries to read it.
AjK 0:e45bbd4486df 22
AjK 0:e45bbd4486df 23 // Note, I used two Mbeds. I could just use one but I didn't want the
AjK 0:e45bbd4486df 24 // software creating the waveforms to steal CPU time. I wanted the receiver
AjK 0:e45bbd4486df 25 // to have all available CPU time it needed. End result, no where enough
AjK 0:e45bbd4486df 26 // with a software soluttion and the SSP failed totally by missing the first bit.
AjK 0:e45bbd4486df 27
AjK 0:e45bbd4486df 28 // With the software solution I did manage to read the data but only to about
AjK 0:e45bbd4486df 29 // 500kHz. The Mbed libs are known to be slow so I could have tried using direct
AjK 0:e45bbd4486df 30 // peripheral usage. But I know from experience that even doing that I would prob
AjK 0:e45bbd4486df 31 // get upto about maybe 1.5MHz. No where near the 6.5MHz needed to read the
AjK 0:e45bbd4486df 32 // AD9951 DSP serial output. Shame on Maxim for having a, err, dumb ass serial
AjK 0:e45bbd4486df 33 // protocol!
AjK 0:e45bbd4486df 34
AjK 0:e45bbd4486df 35
AjK 0:e45bbd4486df 36 }