topic Re: Code not generating (Imput Capture) Interrupt in 8-bit Microcontrollers

Code not generating (Imput Capture) Interrupt

AntE — Tue, 24 Nov 2009 14:33:13 GMT

Hello, Im new in this forum, I have several monts of experienece with microcontrollers (the HCS08QG8 only in assembler), and I have a problem: I need to measure the width of an external pulse generated by a sensor (the ultrasonic sensor SRF05), I have configured the TPM channel 0 as Input Capture with event on Rising Edge, enabled the interrupt in this source, enabled the global mask interrupt, configured the pin 2 of port A (TPM channel 0) as input, but the signal provided by the sensor doesn´t generate the interrupt, and the pulse of the sensor is ok. Debugging I discovered that the flag of the associated port doesn´t get set (reading directly the port with LDA TPMC0SC), tried generating a Timer interrupt and this is neither genereated. I don´t know how to get the interrupt. Any help will be appreciated.

Re: Code not generating (Input Capture) Interrupt

tonyp — Tue, 24 Nov 2009 18:01:36 GMT

Can you post your code?

Re: Code not generating (Imput Capture) Interrupt

AntE — Wed, 25 Nov 2009 01:52:55 GMT

Of course. The whole code is large (the interrupt is only apart of the program), but this is the part relevant of the problem:

; **** main system initialization *******

main:
_Startup:

SEI ; disable interrupts before system initialization

         LDHX   #__SEG_END_SSTACK ; initialize the stack pointer
         TXS

         JSR     MCU_init
         JSR     INITLCD
         JSR     INITTPM
         JSR     INITADC
         CLI              ; enable interrupts

;******** TPM initialization *********

;*
;**************************************
;* INITTPM                                                     *
;*                                                                 *
;* TPMSC                                             *
;* (Timer Overflow interrupt enable) disabled, *
;* bus rate clock (4Mhz), prescaler = 16              *
;*                                                                 *
;* TPMC0SC                                                    *
;* input capture, interrupt enable, Capture on rising *
;* edge                                                           *
;***************************************
INITTPM

MOV $4C,TPMSC;

MOV $44,TPMC0SC
RTS

;****** main body ********

SEN_ACT ;**** this pulse send a "woke up" request to the sensor ****

         BSET    ENREV,PTAD          ; PTA4 <-- 1 Start sensor trigger
         JSR      DLY10U                 ; Delay 10uS aprox
         BCLR    ENREV,PTAD           ; PTA4 <-- 0 Endof trigger pulse

JSR DLY100 ; Waits for sensor pulse and interrupt (0.1 seg)

.....

..... ; //this part process the width obtained

BRA

Re: Code not generating (Imput Capture) Interrupt

tonyp — Wed, 25 Nov 2009 02:11:11 GMT

On first look, everything seems correct.

So, with the exception of the remaining code disabling the TPM at some other place by mistake, I can only think of priority issues. For example, you probably have AD0 or ACMP functionality enabled.

Re: Code not generating (Imput Capture) Interrupt

kef — Wed, 25 Nov 2009 04:34:37 GMT

Aren't # missing ?

MOV #$4C,TPMSC;

MOV #$44,TPMC0SC

Re: Code not generating (Imput Capture) Interrupt

AntE — Wed, 25 Nov 2009 14:17:48 GMT

Yes.... That was the problem, I added the "#" and the interrupt happened.

Thanks a lot Tonyp and Kef.