Need help getting a SCP1000 Altimeter (from SparkFun) to interface with the Pro

Travis_

I'm trying (so far unsuccessfully) to get my PropStick USB to communicate with an SCP1000 altimeter from SparkFun (www.sparkfun.com/commerce/product_info.php?products_id=8161). It uses SPI for communication.

I attached a screen capture of the SPI communication example for a simple command (get the revision id of the board). It's from page 24 of the specification document for the SCP1000 (also attached). The PST output is also attached.

Below is the code I tried using to get the RevId. Using SPI, transmit %00000000 and it should return 03hex, but it just returns %00000000

If some kind soul out there could help me find the err of my ways, I'd greatly appreciate it.

Thanks!

CON
  _clkmode = xtal1 + pll16x                           
  _xinfreq = 5_000_000
   
  #0,MSBPRE,LSBPRE,MSBPOST,LSBPOST                                            'Used for SHIFTIN routines
  #4,LSBFIRST,MSBFIRST                                                        'Used for SHIFTOUT routines

  High  =  1
  Low   =  0
  Out   = %1

  'Pin on Prop Chip for LED Indicator
  PIN_LED = 15

  '//Pin assignments for VTI SCP1000-D01 
  SPI_CSB  = 0    'Chip select out connected to SCP1000 CSB pin
  SPI_SCK = 3    'Clock out to SCP1000 SCK pin
  SPI_MISO = 1    'Data in connected to SCP1000 MISO pin
  SPI_MOSI = 2    'Data out connected to SCP1000 MOSI pin
  SPI_DRDY = 4   'Data ready connected to SCP1000 DRDY pin
  
VAR

  long DataValue, objSPI

OBJ

  Debug   : "FullDuplexSerial"

PUB start | data,i
   
  'start debugger
  debug.start(31,30,0,19200)
    
  'set pin direction for LED to output
  dira[noparse][[/noparse]PIN_LED]~~
   
  'flash the LED to confirm the program is running
  repeat 10
    !outa[noparse][[/noparse]PIN_LED]
    waitcnt(clkfreq / 2 + cnt) '0.5 seconds
   
  'blank the screen
  debug.str(string(16))
   
  'start H48C accelerometer
  debug.Str(string("Starting SPI..."))
  objSPI := false
  objSPI := SPI.Start
   
  'test startup of H48C
  if (objSPI)
    debug.Str(string("Started Successfully!",13))
  else
    debug.Str(string("Failed to Start!",13))

  'display data from H48C & HM55B
  if (objSPI)

    data := %10101010

    data := GetRev
    debug.str(string("GetRev should equal 03h = "))
    debug.bin(data,8)
    debug.str(string(13))

    debug.str(string("Done."))
  else
    debug.str(string("Error: SPI failed to start. Terminating...",13))
                      
PRI GetRev : datar | i

  'set MOSI, CSB, SCK out
  dira [noparse][[/noparse] SPI_MOSI ] := Out
  dira [noparse][[/noparse] SPI_CSB ] := Out
  dira [noparse][[/noparse] SPI_SCK ] := Out
  dira [noparse][[/noparse] SPI_MISO ] := %0
 
  
  'set CLK, MOSI low
  outa [noparse][[/noparse] SPI_SCK ] := Low
  outa [noparse][[/noparse] SPI_MOSI ] := Low

  'set CSB high, then low to reset it
  outa [noparse][[/noparse] SPI_CSB ] := High
  outa [noparse][[/noparse] SPI_CSB ] := Low

  
  repeat 8
    outa [noparse][[/noparse] SPI_SCK ] := High 'set CLK High          
    outa [noparse][[/noparse] SPI_MOSI ] := %0   'transmit bin '0' on MOSI
    outa [noparse][[/noparse] SPI_SCK ] := Low  'set CLK low
    
  repeat i from 7 to 0
    outa [noparse][[/noparse] SPI_SCK ] := High 'set CLK High          
    'read MISO
    if ina[noparse][[/noparse]SPI_MISO] == 1     'read MISO         
      datar |= |< i             ' set bit i HIGH
    else
      datar &= !|< i            ' set bit i LOW
    outa [noparse][[/noparse] SPI_SCK ] := Low  'set CLK low

  outa [noparse][[/noparse] SPI_CSB ] := High
  
  return datar   

shanghai_fool

Attached is a demo that worked for me.

Travis_

shanghai_fool,

Thank you for trying to help. I appreciate it very much.

However, I don't think your code works with the SCP1000 sensor. Your hex codes to pull the Temperature ($84) and Pressure ($7c and $80) are not found anywhere in the SCP1000 specification (attached).

With my circuit & sensor (which I have very little faith in to begin with), the outputs (without any division or manipulation) are: Pressure = 16777215, Temperature = 65535.

I tried changing the hex codes you had for Temp and Pres, but they resulted in the same outputs. Furthermore, I think 65535 is the max value for an integer, which makes the Temperature value look very suspicious.

Travis_

Well, I've gotten a bit further (I think) using BS2_Functions. I've read through the Specification several times and think I'm executing the setup commands needed to get the Temperature and Pressure data.

During my Initialization function, I am pulling the REVID successfully. I am performing a ASIC Self Test, which is passing. The Operation Init function is working. The Status is returning as a success. I'm performing the 'low noise' calibration (which might or might not be needed). So, it looks like the sensor *should* be setup properly.

However, the raw temperature and pressure data is essentially blank/empty.

I have attached the SPIN code as an archive. A picture of the circuit and the specifications are attached to a previous post.

The output from PST is:

Initialize SCP1000...

REVID is ok...00000111
data from SPI_RESET = 00000000
Self Test is ok...00000011
Operation Init is ok...00000011
STATUS is ok...00001100
DATARD8 is ok...00000011
data from reset = 11111110
write(SPI_ADDPTR, $2D) = 00000000
write(SPI_DATARW, $03) = 00000000
write(SPI_OPERATION, SPI_OPERATION_WRITE_DATAWR) = 00000000
data from mode set = 00000000

Starting data capture...

OPSTATUS = 00000011
tempurature = 00000011
pressure = 0000000000001100

So what's the problem? Is my sensor toast? Is my circuit wrong? Is the way I'm pulling the Temperature and Pressure values wrong?

shanghai_fool

Travis_ said...
However, I don't think your code works with the SCP1000 sensor. Your hex codes to pull the Temperature ($84) and Pressure ($7c and $80) are not found anywhere in the SCP1000 specification (attached).

Sorry Travis, mine works OK. The addresses are left shifted 2 bits $84 =$21 (Temp out), $7C = $1F (Data8) and $80 = $20(Data16). I am using mode 0x0A (continous high resolution). This was just a simple test I put together from someone elses code and have not finished the complete driver as yet.

When I sent this, I was in US and did not have access to my lab to test. I have returned homw now and have just benched tested the unit and it still works as before. I did not use the resistors shown in the diagram as it is the only thing connected at this time. I had planned on using the same SPI as the SD card reader which was why the resistors are shown. My display is attached.

Donald