In SX Microcontrollers, SX/B Compiler and SX-Key Tool, RS_Jim wrote:

Good Morning all,

I have been attempting get a reading from an ADC0831 adc converter with SXB.  It appears that with a 50_000_000 clock the clock stream from SHIFTIN is too fast.  when I add a parameter to SpeedMult it gets even faster. I have run it under debug and walked through the subroutine and it seems to be reading the chip OK but when I run it in realtime the results are 0 regardless of the input voltage.  

 

DEVICE          SX48, OSCXT2,' TURBO, STACKX, OPTIONX
FREQ            50_000_000
Adc_clk PIN RD.4 Output
Adc_Dio PIN RD.3 Input
Adc_CS PIN RD.5 Output
  org     bank4_org

bank4  = $
adc_bank = bank4
ENDASM
ADC_RESULTS VAR Byte(16)
Adc_Result  Var ADC_RESULTS(0) 
Adc_Resultw VAR ADC_RESULTS(1)
Adc_resultw_lo VAR ADC_resultw
Adc_resultw_hi VAR ADC_RESULTS(2)
Timer1_R1 VAR ADC_RESULTS(3)
Timer1_R1W   VAR word     'ADC_RESULTS (3)  
Timer1_R1_lo VAR ADC_RESULTS(3)    'Timer_R1
Timer1_r1_hi VAR ADC_RESULTS(4)
Timer1_R2 VAR ADC_RESULTS(5)
Timer1_R2w   Var ADC_RESULTS(5)
Timer1_R2_lo VAR ADC_RESULTS(5)  'Timer1_R2
Timer1_r2_hi VAR ADC_RESULTS(6)   'Timer1_R2 + 1   
Freq_Set Var ADC_RESULTS(7)
Freq_Set_lo VAR Freq_Set 
Freq_Set_hi Var ADC_RESULTS(8)  'Freq_Set + 1


'Subroutines

Read_Adc  Func 2,0


 

Start:

a bunch of port set up code in ASM

 high ADC_CS

GOTO Main
Page_1:
  ADDRESS $200

Func READ_ADC
 low ADC_CS
  SHIFTIN ADC_DIO,ADC_CLK,MSBPOST, adc_Result\8
 
 high ADC_CS
 '__wparam12= adc_Result */ Scale 'scale ADC result to 0-100
 Return   'adc_result
ENDFUNC


MAIN:

Page_2:
  ADDRESS $400
MAIN:
do
 adc_Result = Read_ADC
\Watch adc_Result,8,UBIN
loop 

 

I haven't tracked every step of the assembly code, but as it is leaving the func it seams to be changing the value of the result in __param1 before copying it to adc_result.  I run mode I always get 0 as the result. Walking thru the program I get results that change with the changing voltage on the input to the ADC.

Is my clock really too fast and how do I slow it down? I have commented out the scaling instruction for now until I find the cause of the 0 result.

 

Jim

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