M N / spektRx

Driver for Spektrum (tm) serial receiver, for radio controlled helicopters etc.

spektRx.c@0:80f1104f405a, 2011-10-25 (annotated)

Committer:
offroad
Date:
Tue Oct 25 18:15:55 2011 +0000
Revision:
0:80f1104f405a
Initial release.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
offroad 0:80f1104f405a 1 #include "mbed.h"
offroad 0:80f1104f405a 2 #include "spektRx.h"
offroad 0:80f1104f405a 3
offroad 0:80f1104f405a 4 #define NUM_CHAN (7)
offroad 0:80f1104f405a 5 #define NUM_BYTES_IN_FRAME (2*NUM_CHAN+2)
offroad 0:80f1104f405a 6
offroad 0:80f1104f405a 7 void spektRx_init(spektRx_t* self){
offroad 0:80f1104f405a 8 self -> state = 0;
offroad 0:80f1104f405a 9 self -> valid = false;
offroad 0:80f1104f405a 10 self -> frameNum = 0L;
offroad 0:80f1104f405a 11 }
offroad 0:80f1104f405a 12
offroad 0:80f1104f405a 13 bool spektRx_hasValidFrame(spektRx_t* self){
offroad 0:80f1104f405a 14 return self->valid;
offroad 0:80f1104f405a 15 }
offroad 0:80f1104f405a 16
offroad 0:80f1104f405a 17 void spektRx_runChar(spektRx_t* self, unsigned char c){
offroad 0:80f1104f405a 18 switch(self->state){
offroad 0:80f1104f405a 19 case 0: /* new frame cycle */
offroad 0:80f1104f405a 20 /* first preamble byte received: now expect 2nd preamble byte */
offroad 0:80f1104f405a 21 self->state = (c == 0x03) ? 1 : 0;
offroad 0:80f1104f405a 22 break;
offroad 0:80f1104f405a 23
offroad 0:80f1104f405a 24 case 1:
offroad 0:80f1104f405a 25 /* 2nd preamble byte received: Now expect first data byte */
offroad 0:80f1104f405a 26 self->state = (c == 0x01) ? 2 : 0;
offroad 0:80f1104f405a 27 break;
offroad 0:80f1104f405a 28
offroad 0:80f1104f405a 29 default:
offroad 0:80f1104f405a 30 /* store received byte */
offroad 0:80f1104f405a 31 self->data[self -> state - 2] = c;
offroad 0:80f1104f405a 32 ++self->state;
offroad 0:80f1104f405a 33
offroad 0:80f1104f405a 34 if (self->state == NUM_BYTES_IN_FRAME){
offroad 0:80f1104f405a 35 /* one complete frame was received.
offroad 0:80f1104f405a 36 * - Copy the data
offroad 0:80f1104f405a 37 * - mask out bits 10..15
offroad 0:80f1104f405a 38 */
offroad 0:80f1104f405a 39 int ix;
offroad 0:80f1104f405a 40 for (ix = 0; ix < NUM_CHAN; ++ix){
offroad 0:80f1104f405a 41 self->out[ix] = ((self->data[2*ix] & 3) << 8) | self->data[2*ix+1];
offroad 0:80f1104f405a 42 }
offroad 0:80f1104f405a 43
offroad 0:80f1104f405a 44 /* output data is now valid */
offroad 0:80f1104f405a 45 self->valid = true;
offroad 0:80f1104f405a 46 ++self->frameNum;
offroad 0:80f1104f405a 47
offroad 0:80f1104f405a 48 /* ready for the next frame */
offroad 0:80f1104f405a 49 self->state = 0;
offroad 0:80f1104f405a 50 } /* if frame complete */
offroad 0:80f1104f405a 51 } /* switch state */
offroad 0:80f1104f405a 52 }
offroad 0:80f1104f405a 53
offroad 0:80f1104f405a 54 void spektRx_runSerial(spektRx_t* self, Serial* s){
offroad 0:80f1104f405a 55 while(s -> readable())
offroad 0:80f1104f405a 56 spektRx_runChar(self, s -> getc());
offroad 0:80f1104f405a 57 }
offroad 0:80f1104f405a 58
offroad 0:80f1104f405a 59 unsigned short* spektRx_getChannelData(spektRx_t* self){
offroad 0:80f1104f405a 60 return (unsigned short*) self -> out;
offroad 0:80f1104f405a 61 }
offroad 0:80f1104f405a 62
offroad 0:80f1104f405a 63 float spektRx_getChannelValue(spektRx_t* self, char ixChan){
offroad 0:80f1104f405a 64 return (float)self->out[ixChan] / 512.0f - 1.0f;
offroad 0:80f1104f405a 65 }
offroad 0:80f1104f405a 66
offroad 0:80f1104f405a 67 long spektRx_getFrameNum(spektRx_t* self){
offroad 0:80f1104f405a 68 return self->frameNum;
offroad 0:80f1104f405a 69 }
offroad 0:80f1104f405a 70
offroad 0:80f1104f405a 71 void spektRx_invalidateFrame(spektRx_t* self){
offroad 0:80f1104f405a 72 self->valid = false;
offroad 0:80f1104f405a 73 }