RESOLVED - Found error in the BOM - inverted part was placed on board.
On Tuesday, February 17, 2015 at 10:19:04 AM UTC-5, ulrichd wrote: > > - > > Symptom: > - > > > - > > On power-up, PWRONRSTn (B15 – PORZ) – pin 2 of U16 > becomes de-asserted while WARMRSTn (A10 – NRESET_INOUT) stays > asserted (low). > > > - > > > - > > > - > > Below is a summary of the current situation and test executed. Any > feedback is greatly appreciated. > - > > > - > > Same symptoms on 5 circuit boards. New design – based on BeagleBone > Black. > - > > 24mHz oscillator is oscillating > - > > 32Khz oscillator is not oscillating > - > > Measured resistance to ground on WARMRSTn (A10 – NRESET_INOUT) using > DVM – about 15K ohms – no short. > - > > Removed C35 based on Paul’s recommendation – no effect > - > > Removed R9 based on Biser’s recommendation – no effect > - > > Checked all voltages and all align with datasheet > - > > 3.3V operation for I/O > - > > VDD_MPU is set for OPP_100 – is there something else that needs to > be setup? > - > > Found a note in the BeagleBone notes – revision A6 – referencing AND > gate. This is not in our design since it is not shown in schematic. Could > this be a factor? > > > > > > A6 > > 1. Moved the enable for the VDD_3V3B regulator to VDD_3V3A rail. Change > was made to reduce the delay between the ramp up of the 3.3V rails. > > 2. Added a AND gate to the SYS_RESETn circuitry. There is a small chance > that on power up the nRESETOUT signal on the processor may go high, > causing the SYS_RESETn signal to go HI before it should. This change > reenforces the reset with the PORZn reset signal. > 3. Added optional zero ohm resistor to tie GND_OSC0 to system ground. > > > > > > > 7/25/2013 > > > > > > GC > > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
