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Using OWI with PGA900-EVM GUI

David Kerr
Prodigy 140 points
Other Parts Discussed in Thread: PGA900

I'm trying to use OWI with the PGA900 EVM to read/write to the PGA900.  Is it possible?

I) J12 is closed, J13 is open.  I loaded the program into DEVRAM using I2C.  The program is running OK.  The OWI registers look correct.  So far, so good.

2) What's the right sequence of button-clicks to use OWI?  If I go into 'digital interface' mode, set activation mode to "through pulse" and click "OWI", the GUI goes back to "Microcontroller" mode, which blocks my access to EEPROM and registers.

3) Do I have to set the OWI baud rate somewhere to match the GUI default?  (4800)

4) OWI_XCVR_EN starts out enabled when I load the firmware, but eventually becomes disabled after I try the OWI communication.

5) If I understand correctly, it's impossible to use only OWI with the PGA900.  OWI has to be activated first, either through firmware or writing to the OWI registers with another digital interface.

Any suggestions would be appreciated.  Thanks.

  • 0
    TI__Intellectual 2865 points
    Hi David,

    To activate OWI through the use of an activation pulse, firmware on the device has to be configured to allow the the pulse to put the PGA900 in the proper mode, as described on page 42 of the datasheet.

    When you press the "OWI" button on the GUI, it is sending the proper activation pulse levels, going from 5 V to 7.5 V back 5 V.
    When the devices receives this activation pulse, the device receives an activation interrupt, written to the OWI_INTERRUPT_EN register. The firmware on the device needs to have an OWI activation interrupt service routine, that does the following:

    (a) Clear the OWI Activation Interrupt by writing 1 to OWI_INT_RW bit in OWI_INTERRUPT register.
    (b) Enable OWI by writing 1 to OWI_EN bit in DIG_IF_CTRL register.
    (c) Connect OWI transceiver to VDD pin by writing 1 to the OWI_XCR_EN bit in DIG_IF_CTRL register.
    (d) If the OWI master will communicate to PGA900 with the microprocessor in reset, reset microprocessor by writing 1 to MICRO_RESET bit in MICRO_INTERFACE_CONTROL register and enable digital interface by writing 1 to IF_SEL bit in the MICRO_INTERFACE_CONTROL. If OWI master will communicate with PGA900 while microprocessor is running, then the COMBUF registers will be used for communication.