How to activate TRK-MPC5606B Vaux (33905)

[deanhansen]

Unsuccessful at activating Vaux on development board.  Normally un-populated T1 has been updated with PNP: BCP5216 and R22 left in place.  Presently using board in debug mode. Board is initialized with following sequence:

  0x84 -> INIT register       // set Vaux to 5V

  0x00 -> WD register        // set to normal (debug) mode

  0xC0 -> CAN register      // enable CAN

  0x8C -> REG register      // "attempt" to enable Vaux

But no Vaux (5v) voltage at associated dev board pin

Voltage at T1 emitter and base are equal and at supply but no voltage on collector.

I am assuming SPI transfer with 33905 is working since I have CAN activity

Post initialization readback of registers shows:

  REG register = 0x08

  REG flags     = 0x00

Does any one know if I am missing either a hardware mod or software initialization problem?

[TomasVaverka]

Hi Dean,

I assume it is a software problem. VAUX is disabled by default (bits Vaux[1:0] = 0b00) and must be turned ON by SPI in Normal mode as shown in Table 8 of the datasheet. In order to do that, the SBC has to leave the Init mode and enter the Normal mode. This is done using the SPI watchdog refresh command 0x5A00. Then you can enable Vaux by sending 0x8C to the Regulator register.

I hope it helps.

Best regards,

Tomas