DC Motor ESC issue 12F683

Posted to the melabs support forum first on accident...

Looks like far more people use these forums so I am reposting here.

So I thought I would pickup this hobby again and start by making something simple.

I chose to make a basic Electonic Speed Control for a small park flyer I have on my bench.

For the past few days I've been bread-boarding FET circuits to run the motor (that's not the issue) and I am working on PBP code to run it.

It works as far as controlling the speed of the motor from the transmitter. But I am having an issue and I am at a loss for what I have missed.

Some background: I am using a DMX2 Transmitter and Receiver. These things 'mate-up' when you turn them on. You first turn on the TX and then the RX. About 5-10 seconds later they are connected. During this time it's doing some sort of hand-shake routine I guess...

The problem: My PIC12F683 based ESC starts sending PWM as soon as I turn on the circuit and goes to about 50% throttle until the handshake period is over. Once it's mated up, the motor goes to 0 throttle. Obviously I don't want that as my plane would be either cutting my hand or taking off without control before the mating ritual is over.

I am fairly certain my electronics are good and there are no stray signals on the dc or in the FET circuit. I've scoped all signal aspects of the circuit at start-up and the only one I see prior to the rx coming on-line is the ~162ms pulse train coming from the hardware pwm on the pic.

I suspect it has something to do with how I am configuring the control registers of the chip or maybe the meProgrammer settings? It seems like what is happening is the PWM is running right at boot?

Below is the 'code' so far. As i said, it works well enough except for the whole start-up problem.

Thoughts and/or suggestions?

Code:

'**************************************************************** '* Notes : DC motor ESC written for PIC12F683 * '* : Takes Pulsin Input from RX on GPIO.3 * '* : HPWM FET Driver Output on GPIO.2 * '* : Debug Ouput on GPIO.5 * '* ; Receiver Sends pulses between 109 & 189 * '**************************************************************** #CONFIG __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF & _BOD_ON #ENDCONFIG ADCON0 = 0 'A/D Off CMCON0 = 7 'Comparators Off ANSEL = 0 'Set all Digital WPU = 0 'turn off pull-ups OPTION_REG = %10000000 'Set GPIO.2 i/o, pull-ups off, prescaler to tmr1 GPIO = 0 'All outputs =0 on boot TRISIO.2 = 0 'Set GPIO.2 Data In osccon = %01100000 'Set Oscillator to 4mhz Include "modedefs.bas" DEFINE osc 4 'Set compiler scale to 4mhz' DEFINE PULSIN_MAX 1000 'Set Pulse Capture Window Max to 1 second DEFINE DEBUG_REG GPIO 'Set Debug Bank to GPIO DEFINE DEBUG_BIT 5 'Set Debug Output port to GPIO.5 DEFINE DEBUG_BAUD 9600 'Set Debug Serial Baud Rate DEFINE DEBUG_MODE 1 'Invert Serial Bits DEFINE DEBUGIN_REG GPIO 'Set Debug Input Bank to GPIO DEFINE DEBUGIN_BIT 4 'Set Debug Input Port to GPIO.4 DEFINE DEBUGIN_MODE 1 'Invert Serial Bits Received rxin var GPIO.3 'Input from rc receiver txout var GPIO.2 'pwm output to FET Driver Circuit rxval var BYTE 'Raw Pulse Value from RC receiver adjp var byte 'Scaled Value for ccp1 duty cycle adjp = 0 rxval=0 'wait for a stable low arm: pulsin rxin,1,rxval 'Get a pulse if rxval>115 then goto arm 'wait for something below 115 main: pulsin rxin,1,rxval 'get a pulse adjp = (((rxval - 109)*5)/16)*10 'scale the input between 109-189 to make it 0-250'ish HPWM 1,adjp,62 'set the pwm debug "Duty Cycle:",#adjp,10 'send PWM duty cycle text to console goto main