Serin Not Recognizing Qualifier From Another PIC

[JESmitter]

Hi Experts,

I have a very simple task to perform. I need to pass a couple of bytes from one PIC12F683 to another PIC12F683 and can't get it to work! I've tried everything that I could think of and can't pinpoint the problem. I am using GPIO.5. I have been very successful with SERIN in other projects. In fact, I am receiving packets from a radio receiver using GPIO.0 on this same PIC and it works fine. For some reason GPIO.5 is not cooperating.

The Weak Pullup on GPIO.5 (DataOut) pin is enabled and the data is transmitted and received True". My idle state is in the "Mark" condition (High).

The TX PIC sends this -
Serout DataOut,1,[ProgID,IDByte] ' Xmit Qualifier and new ID

The TX PIC is sending the packet out. I have my oscilloscope connected to verify it. I don't think the Qualifier is being recognized or processed. What am I missing???

'''''''''''''''''''''''''''''''''''''''''''''''''' ''''''''''''''

Receiver Code -

#CONFIG
; set CONFIG1 for internal oscillator, watchdog on, MCLR pin as OFF
__config _WDTE_ON & _MCLRE_OFF & _INTOSCIO & _PWRTE_ON

#ENDCONFIG


OSCCON =
100000 ' Set system clock 4MHz(1MHz internal w/x4 PLL enabled)


DEFINE OSC 4 ' Calibrate PBP timing to 4MHz system clock

OPTION_REG = 000000 ' Enable Weak Pullups Control
WPU = 100000 ' Disable all Weak Pullups except GPIO.5
ANSEL = 0000 ' No analog inputs
TRISIO = 1001 ' Make GP1, GP2 outputs. GP0, GP3, GP4 & GP5 = inputs
CMCON0 = 0111 ' Turn off comparators
ADCON0 = 0 ' Turn off A/D


IDByte var byte ' Receiver ID.
AlarmByte var Byte ' Received Alarm
AlarmVal var byte ' Alarm Zone(s)
RxIn var GPIO.0 ' Incoming Packet Port
Z1Alarm var GPIO.2 ' Zone1 Alarm LED
Z2Alarm var GPIO.1 ' Zone2 Alarm LED
ByteSum var Byte ' IDByte & AlarmByte Sum Value
ChkSum var byte ' ChkSum value to test
ProgID var byte ' Programmer Present Verify
PrgIn var GPIO.5 ' Programmer Detect & Data Port
IDByteRx var byte ' New IDByte
ProgIDRx var byte ' Received Programmer ID

'''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''
MainLoop:

Serin PrgIn,1,5000,PassProg,[ProgIDRx],IDByteRx ' Wait for 5 seconds for new I.D. to arrive
if ProgIDRx = $A THEN GOSUB UpdateID ' Verify arrival and execute UpdateID Subroutine
PassProg: ' No Packet received - Timeout reached - Jump out and repeat
PAUSE 500
GOTO MainLoop

UpdateID:
Z1Alarm = 1 : Z2Alarm = 1 ' LEDs to Confirm programing Subroutine
PAUSE 500
Z1Alarm = 0 : Z2Alarm = 0 ' Turn off LEDs
PAUSE 1000
Z1Alarm = 1 : Z2Alarm = 1 ' LEDs to Confirm in programing mode
PAUSE 1000
Z1Alarm = 0 : Z2Alarm = 0 ' Turn off LEDs
IDByte = IDByteRx
Write 1, IDByte ' Write new ID to EEPROM

RETURN


END

I appreciate your help. Thank you!

[HenrikOlsson]

Hi,
I have not looked closely at your code yet and I don't know if this will make any difference but I did react to the following:

The Weak Pullup on GPIO.5 (DataOut) pin is enabled and the data is transmitted and received True".

Please note that the WPU is turned off when pin is configures as an output. See section 4.2.2 in the datasheet.

Apart from that, are both PICs on the same PCB, sharing the same power supply and, more importantly, the same ground?

[JESmitter]

Thank you Henrik for you prompt reply.

The Receiver PIC's GPIO.5 is indeed configured as an input and the two systems do share a common ground.

Transmit PIC - GPIO.2 is set as an output and the outbound packet is sent by SEROUT DataOut,1,[ProgID,IDByte]

Receive PIC - GPIO.5 is set as an input and is configured to receive the packet by SERIN PrgIn,1,5000,PassProg,[ProgIDRx],IDByteRx

I didn't include the transmitter PIC code because the oscilloscope verified that the packet is being sent.

I wonder... what logic state should SERIN be idling at? I have it at logic high to generate a "mark" condition.

[amgen]

two thoughts looking at your code.........
...ProgIDRx = $A............ did you CLEAR ProgIDRx after reception and might need to be ....$"A" not sure but

[JESmitter]

Hi Amgen,

Thanks for the reply. Yes, ProgIDRx is cleared. And its value is $A (or10). But, I haven't been able to receive it yet because nothing is being received. SERIN always exits upon the 5 second Timeout variable "PassProg" as if nothing is present at the pin.

And, in addition, If I had noise on the pin, SERIN would never time out. So, that indicates that SERIN is, at least, partially working, I would think.

[rocket_troy]

I don't really use serin so I can't be of much help, but just to educate me: isn't the contents inside the square brackets a qualifier or filter - like the WAIT modifier in serin2?

Troy