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[MPC5777M]Unable to write to FlexRay registers

Question asked by Uma Balakrishnan on Mar 13, 2017
Latest reply on Mar 14, 2017 by Uma Balakrishnan


We are unable to write to the following Message Buffer registers for FlexRay in the MPC777M EVB:



We make sure that both conditions for writing to these registers: POC:config and MB_DIS are fulfilled.
We are able to write to FR_MBFIDRn and also set the appropriate bits in FR_MBCCSRn.

From the attached fr.c file, the functions are called in the following order:

  1. flexray_pin_configuration() -- Configuring the pins
  2. Fr_init()  -- This function configures the CC, enables the FlexRay module and then commands the CC to transition to the POC:Config state via the FR_POCR register
  3. Fr_set_configuration() -- Configures the protocol engine via FR_PCRn registers
  4. Fr_buffers_init() -- Configures the message buffers (this where we face the register write problem). Before attempting the write, we check the EDS bit in the FR_MBCCSRn register to make sure MB_DIS is satisfied.
  5. Fr_leave_configuration_mode() -- Exits POC:Config mode and wait for POC:Ready


Are there any further requirements we missed?

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