Micromega uM-FPU V1.0 woes

Comments

• Bruce Bates Posts: 3,045

  2004-10-29 21:03 edited 2004-10-29 21:03

  Sunktruck -
  
  Have you placed the following conditional compilation code near the top of your program or at least used the proper teime delay extracted from this coding?
  
  #IF ($STAMP = BS2SX) OR ($STAMP = BS2P) #THEN
  ResetTime CON 160
  #ELSE
  ResetTime CON 65
  #ENDIF
  
  Have you also tied pins 3. 4. 5. and 6 to ground on the uM-FPU chip?
  
  If so, a complete look at your coding might then be appropriate to try and locate the source of the problem.
  
  Regards,
  
  Bruce Bates
• sunktruck Posts: 10

  2004-10-29 21:35 edited 2004-10-29 21:35

  Bruce,
  Thanks for your input. I do have your conditional compile statements in "my" code. However I only have pins 3,4, and 6 tied to ground. Pin 5 looked like an output pin on the data sheet that is for the FPU (which shows pin 5 unconnected). Also, I assume "my" code is correct since it is the code examples provided by uM.
  
  I was also wondering if the FPU needed a "pull down" resistor on the data line.
  
  Thanks again,
  Greg
• Bruce Bates Posts: 3,045

  2004-10-29 22:09 edited 2004-10-29 22:09

  Greg -
  
  As I remember pin 5 is a test-pin and presuming you're not using it should be tied to ground. My information comes from the uM-FPU information on the Parallax website. Included in that information on the Parralax web site are sample programs as well. All of that information and more as well can be found here:
  http://www.parallax.com/detail.asp?product_id=604-00030a
  
  Regards,
  
  Bruce Bates
• sunktruck Posts: 10

  2004-10-30 02:48 edited 2004-10-30 02:48

  Bruce,
  You are correct in stating pin5 is a test pin, I have since tied it to ground using a 220ohm resistor (to limit current just in case). The information you are looking at is the same that I have been staring at for the past two days <bangs head on desk>. All the sample programs on the Parallax website yields the same results - waiting for the data pin to go low (as described in my first post). I am starting to think that I have a bad FPU - go figure a hardware guy blaming hardware not software. I have also tested using the "default" pins 14 and 15, with the same frustrating results.
• sunktruck Posts: 10

  2004-11-01 15:10 edited 2004-11-01 15:10

  UPDATE:
  I had to use three seperate BS2 pins (CLK, SI, SO) to facilitate proper operation. I also had to insert a 5ms PAUSE in the SYS_COMMAND routine. It works like a champ now, but it takes 3 I/O pins
• camt Posts: 45

  2004-11-01 19:09 edited 2004-11-01 19:09

  Greg,
  
  There should be no problem connecting the uM-FPU to pin 6 and 7 on the BS2p. I've just wired up a test circuit and all the test routines run fine. It makes me think there may be some other interaction. I'm glad the workaround has got you going, but a 5 ms delay is a huge delay and should definitely not be required.
  
  In answer to your earlier questions, there is no pull-down required on the data lines, a 5.6K pulldown is internal to the chip. The proper connection is shown on the Micromega website at:
  http://www.micromegacorp.com/connection.html
  
  I'd be happy to track this down further, and would suggest that you email me at:
  support@micromegacorp.com
  
  Regards,
  Cam Thompson
  Micromega Corporation
• sunktruck Posts: 10

  2004-11-04 03:22 edited 2004-11-04 03:22

  With Cam's assistance, we determined that my BS2p is at fault. Some of the pins on my BS2p goto 5V during an INPUT call, thus always reading the pin as high. Thanks to all for your help. Time to order another stamp.