MMA7455L breakout board manufacturing tests

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Manufacturing prototype test

This is a simple test to verify the connections on the board.

Test connections

Bus Pirate Direction MMA7455L Description
MOSI SDA/SDI Master Out, Slave In
MISO SDO Master In, Slave Out
CLK SCL/SPC Clock signal
CS CS Chip Select
+3.3V3.3VPower supply
GND GND Ground

Bus Pirate setup

Connect the Bus Pirate to the chip as shown in the table.

HiZ>m<<<mode command
1. HiZ
...
5. SPI
...
(1)>5<<<SPI mode
Select output type:
1. Open drain (H=Hi-Z, L=GND)
2. Normal (H=3.3V, L=GND)
(1)>2<<<normal pinout
Ready
SPI>

Configure the Bus Pirate for SPI mode. Chose all the default settings except output type. Choose normal pin outputs.

SPI>W<<<enable power supplies
Power supplies ON
SPI>

The chip is powered by the Bus Pirate, enable the power supplies (W).

Check the connection

SPI>[0x1A r]
/CS ENABLED
WRITE: 0x1A <<<read I2C address register
READ: 0x1D<<<read value from register
/CS DISABLED
SPI>

Enter '[0x1A r]' and verify that the READ: value is 0x1D.

Automated manufacturing test

This test uses the Bus Pirate to check the MMA7455 during manufacturing.

Options

[help menu]

-------------------------------------------------------------------------
Bus Pirate-MMA7455L breakout board
SELF TEST utility v0.1 (CC-0)
http://www.dangerousprototypes.com

-------------------------------------------------------------------------

-------------------------------------------------------------------------

Help Menu
Usage:
MMAtest.exe -p device [-s speed]

Example Usage: MMAtest.exe -p COM3

Where: -p device is port e.g. COM3
-s Speed is port Speed default is 115200

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Success

--------------------- Starting a new Test-------------------------
Opening Bus Pirate on COM5 at 115200bps...
Configuring Bus Pirate ....
Going into Binary Bitbang mode..
Entering binary mode...ok
Going into SPI mode.. Switching to SPI mode ..ok
Power on...
Enabling power, normal pin outputs..
CS High : 0x03....
CS Low : 0x02....
Sending 0x1A....
Got reply: 0X1D
Self test status with MMA7455L breakout board: **** PASS! *****
CS High : 0x03....
Exiting SPI mode/reseting Buspirate..

Successful test.

Failure

--------------------- Starting a new Test-------------------------
Opening Bus Pirate on COM5 at 115200bps...
Configuring Bus Pirate ....
Going into Binary Bitbang mode..
Entering binary mode...ok
Going into SPI mode.. Switching to SPI mode ..ok
Power on...
Enabling power, normal pin outputs..
CS High : 0x03....
CS Low : 0x02....
Sending 0x1A....
Got reply: 0X00
Self test status with MMA7455L breakout board: !!!! FAILED! !!!!
CS High : 0x03....
Exiting SPI mode/reseting Buspirate..

Failed test.

Notes

The automated test app uses the Bus Pirate to test the connection to the MMA7455L:

  1. Enter BBIO mode
  2. Enter SPI mode
  3. Enable power
  4. Setup SPI (normal pin outputs, etc)
  5. Set CS high
  6. Set CS low
  7. Send 0x1A
  8. Read one byte
  9. Set CS high
  10. Verify read=0x1D
  11. Exit SPI mode (to disable power and pins)
  12. Repeat from 2