9S08PA16 continually resetting - config problem?

[Circlotron]

Trying to get my first bit of .asm code running on a 9S08PA16. Kinda getting there. Currently it's just a loop flashing a LED.  . The thing is, the reset pin continually pulses low for 4uS every 7.07mS. Running off a 20MHz xtal. Interrupt bit is set, timer is stopped. Watchdog timer is stopped. LVD disabled. Just thinking something is timing out somewhere. There is just a ridiculous amount of config registers in this thing...

[jaromir]

I believe the watchdog is still running.
Show us the code. At least the hardware initialization portion, but since it's just LED flasher, probably whole source code will be OK, too.

[Circlotron]

Okay, here it is. Tabs spaces are being a bit silly...

Code: [Select]

*****************************************
$BASE 10T

PORTA               EQU     $00
PORTAIE EQU $30B8
PORTAOE EQU $30B0

PORTB               EQU     $01
PORTBIE EQU $30B9
PORTBOE EQU $30B1

PORTC            EQU     $02
PORTCIE EQU $30BA
PORTCOE EQU $30B2

PORTD               EQU     $03
PORTDIE EQU $30BB
PORTDOE EQU $30B3

PORTE               EQU     $04
PORTEIE EQU $30BC
PORTEOE EQU $30B4





ADC_SC1 EQU $10 ;Status and Control Register 1 page 466
ADC_SC2 EQU $11 ;Status and Control Register 2
ADC_SC3 EQU $12 ;Status and Control Register 3
ADC_SC4 EQU $13 ;Status and Control Register 4
ADC_RH EQU $14 ;Conversion Result High Register
ADC_RL EQU $15 ;Conversion Result Low Register
ADC_CVH EQU $16 ;Compare Value High Register
ADC_CVL EQU $17 ;Compare Value Low Register
ADC_APCTL1 EQU $30AC ;Pin Control 1 Register
ADC_APCTL2 EQU $30AD ;Pin Control 2 Register

WDOG_CS1 EQU $3030 ;Watchdog Control and Status Register 1 page 517

TSC         EQU $20 ;page
TCNTH EQU $21 ;page
TCNTL EQU $22 ;page
TMODH EQU $23 ;page
TMODL EQU $24 ;page
TSC0         EQU $25 ;page 277
TCH0H EQU $26 ;page 280
TCH0L EQU $27 ;page 281
TSC1         EQU $28 ;page 277
TCH1H EQU $29 ;page
TCH1L EQU $2A ;page
ACMP EQU $2C ;page 499 analog comparator S/C

;internal clock sources
ICS_C1 EQU $3038 ;ICS Control Register 1 page 191
ICS_C2 EQU $3039 ;ICS Control Register 2 page 192
ICS_C3 EQU $303A ;ICS Control Register 3 page 193
ICS_C4 EQU $303B ;ICS Control Register 4 page 193
ICS_S EQU $303C ;ICS Status Register   page 194
ICS_OSCSC EQU $303E ;OSC Status and Control page 195

PMC_SPMSC1 EQU $3040 ;sys pwr management page 52

;VectorStart        EQU     $FFB0 ;page 56
**********************************
;2048 bytes RAM starts at $0040
EXAMPLE_MSB     EQU     $40 ;example
********************************************************************************
TRST         EQU 4 ;timer reset
TSTOP EQU 5 ;timer stop
TOF         EQU 7 ;timer overflow
********************************************************************************
                ORG     $C000 ; <--- new flash start

START BSET TSTOP,TSC ;stop timer
                SEI                      ;no interrupts
LDA #%00000000
STA WDOG_CS1 ;watchdog timer off, bit 7

;set or clear outputs before changing any DDR bits to 1

MOV     #%00000000,PORTA
MOV     #%00000000,PORTB ;
MOV     #%00000000,PORTD

;DDRs
LDA #%00000000
STA PORTAIE
LDA #%00000000
STA PORTAOE
LDA #%00000000
STA PORTBIE
LDA #%00000000
STA PORTBOE
LDA #%00000000
STA PORTCIE
LDA #%00000000
STA PORTCOE
LDA #%00000000
STA PORTDIE
LDA #%00000001
STA PORTDOE
;LDA #%00000000
;STA PORTEIE
;LDA #%00000000
;STA PORTEOE

LDA #$96 ; = #10010110
STA ICS_OSCSC

LDA #$80 ; = #10000000 BDIV = 0, prescaler = 1
STA ICS_C1

LDA #$00
STA ICS_C2

LDA #$00
STA PMC_SPMSC1

                CLC
RSP
                CLRX
                CLRA
*******************************************************************************
TOP BSET 0,PORTD ;LED on
LDHX #1000 ;1000 = 400uS

TOPLOOP AIX #-1 ;2 8 cyc
CPHX #0 ;3 400nS per loop, 2.5MHz
BNE TOPLOOP ;3 400nS/8 = 50nS per cyc @ 20 meg xtal
;  buss = xtal

BCLR 0,PORTD ;LED off
LDHX #1000

BOTLOOP AIX #-1
CPHX #0
BNE BOTLOOP

JMP TOP
*******************************************************************************
                ORG     $FFFE ;Reset
                FDB     START
*******************************************************************************


[Circlotron]

Actually the LED is somewhat more than flashing. With the current code it is 400uS on, 400uS off, but a bit jittery because of the constant resets.

[jaromir]

Manipulating the watchdog is a bit more complicated than just writing to WDOG_CS1 straight.
Take a look at section 21.3.2 of reference manual https://www.nxp.com/docs/en/reference-manual/MC9S08PA16RM_Rev.1.pdf Watchdog is enabled after POR, to reconfigure it, all watchdog registers - except of CNTH/CNTL - must be written.

This is how I disable the watchdog - in C, but you get the idea -

Code: [Select]

    WDOG_TOVALL = 0x00;
    WDOG_TOVALH = 0x10;
    WDOG_CS2 = 0x01;
    WDOG_CS1 = 0x20;


[Circlotron]

jaromir, you da man! 

It says there "The new configuration takes effect only after *all* registers except WDOG_CNTH:L are written once after reset. Otherwise, the WDOG uses the reset values by default.

So I put the following and it works. I'm sure there will be other questions as I proceed.

Code: [Select]

;For watchdog setting to take effect, all regs must be written to
;even if it the same as their default reset values!!!
 
LDA #$20
STA WDOG_CS1 ;watchdog timer off
LDA $01
STA WDOG_CS2
LDA #$10
STA WDOG_TOVALH
LDA #$00
STA WDOG_TOVALl