The 8.2 (or 8.3) Battery Voltage Bug

[eugenebrooks]

Originally Posted by Kevin Watson

Just FYI, the camera code uses a serial port driver that teams have been using for over a year now without a problem. The camera, once initialized, only sends a few hundred bytes of information per second, which is easily handled by the PIC microcontroller.

-Kevin

The problem appears to be some form of memory stomping, in the IFI default
code, or in the controller chip itself. I don't believe that it is a bug in the
camera code per-se, although the use of the camera code increases the
severity of the problem. We backed out of all of our interrupt/timer based
control at the Portland regional in response to this problem as there was
no way we could keep our robot running otherwise. We have seen problems
in very simple code. Below are the only lines of custom code, using
the recently published default code.

At one point whether or not the periodic printf statements appeared on
he download console depended upon whether or not we had
static int counter;
or
static int counter = 0;
for the declaration of "counter". This problem comes and goes over
a day, in the morning it is consistent but when attempting to reproduce
it with the same code in the afternoon one can't after several tries.
I am presuming that the memory location
of "counter" moves between the implicitly initialized segment, from the
explicitly initialized segment, with the declaration change and this changed
the arrangement of memory. Whether or not memory is actually getting
stomped is something a little more random in the controller.

An option question is, given the problems with the 2006 controller,
whether or not FIRST would be willing to allow the use of the 2005
controller at regional events. We have not seen any of these problems
on the 2005 controller.

Eugene



/************************************************** *****************************
* FUNCTION NAME: Process_Data_From_Master_uP
* PURPOSE: Executes every 26.2ms when it gets new data from the master
* microprocessor.
* CALLED FROM: main.c
* ARGUMENTS: none
* RETURNS: void
************************************************** *****************************/

struct rpmpower {
int rpm;
int power;
};
/* This table is constructed by using the manual RPM control to set
RPM values manually and then reading off the required power for that RPM.
*/
#define RPMPOWERTABLESIZE 9
struct rpmpower rpmpowertable[RPMPOWERTABLESIZE] = {
1300, 160,
1400, 161,
1500, 167,
1600, 168,
1700, 170,
1800, 177,
1900, 181,
2000, 189,
2100, 193
};
int RPM2Power(int rpm) {
int RetPower;
int i;
if(rpm <= rpmpowertable[0].rpm) return rpmpowertable[0].power;
if(rpm >= rpmpowertable[RPMPOWERTABLESIZE-1].rpm) return rpmpowertable[RPMPOWERTABLESIZE-1].power;
for(i=0; i<(RPMPOWERTABLESIZE-1); i+=1){
if(rpmpowertable[i].rpm < rpm && rpmpowertable[i+1].rpm >= rpm){
RetPower = rpmpowertable[i].power + ((rpm - rpmpowertable[i].rpm) * (rpmpowertable[i+1].power - rpmpowertable[i].power)) / (rpmpowertable[i+1].rpm - rpmpowertable[i].rpm);
break;
}
}
return RetPower;
}


void Process_Data_From_Master_uP(void)
{
int Target;
int BallWheelPower;
static int counter; /* Does not work if not initialized to zero! */

Getdata(&rxdata);

/* Control of the drive motors.
*/
if(rc_dig_in08 == 1) {
pwm01 = p1_y;
pwm02 = p3_y;
pwm03 = p1_y;
pwm04 = p3_y;
}
else {
pwm01 = STOP;
pwm02 = STOP;
pwm03 = STOP;
pwm04 = STOP;
}

/* Pan Control
*/
if(p3_sw_trig == 1 && rc_dig_in12 == 0) {
pwm06 = STOP + 20;
}
else if(p2_sw_aux2 == 1 && rc_dig_in11 == 0){
pwm06 = STOP - 12;
}
else{
pwm06 = STOP;
}
if(rc_dig_in06 == 0){
pwm06 = STOP;
}

/* Ball lift control.
*/
if(p2_sw_top == 1 && rc_dig_in07 == 1) {
pwm05 = 254;
}
else if (p2_sw_trig == 1 && rc_dig_in07 == 1){
pwm05 = 1;
}
else {
pwm05 = STOP;
}

/* Ball wheel speed control.
*/
Target = (int)1200 + (int)3 * (int)p4_x;
BallWheelPower = RPM2Power(Target);
if(rc_dig_in10 == 0) {
pwm07 = STOP;
}
else {
pwm07 = BallWheelPower;
}

/* Ball shooter fire control
*/
if(p2_sw_aux1 == 1 && rc_dig_in09 == 1) {
pwm08 = 254;
}
else {
pwm08 = STOP;
}


if(counter % 40 == 2) {
printf("p1_y = %d, p3_y = %d, BWP = %d, TargetRPM = %d, p4_x = %d\r",
(int)p1_y, (int)p3_y, (int)BallWheelPower, (int)Target, (int)p4_x);
}

counter += 1;

if (user_display_mode == 0) {
if(rc_dig_in12 == 1) { /* Right pan limit. */
Switch1_LED = 1;
}
else {
Switch1_LED = 0;
}
if(rc_dig_in11 == 1) { /* Left pan limit. */
Switch2_LED = 1;
}
else {
Switch2_LED = 0;
}
}
else {
User_Mode_byte = backup_voltage * 10;
}

Generate_Pwms(pwm13,pwm14,pwm15,pwm16);

Putdata(&txdata); /* DO NOT CHANGE! */
}