Hi there,
I have just received my prototype PCBs back for a system based around the AM3359 / TPS65217C. Indeed the system will look remarkably similar to the Beagle Bone Black, so close in fact that I would expect the BBB Software to run on this platform without any modification.
So I must have made a mistake somwhere because that is not the case :-)
I have done the usual smoke tests, and everything looks good. that is my front end PSU is fine (supplying the PMIC). Rails from the PMIC look good, I see a 24MHz clock come up as well. if I insert a uSD card (on bus MMC0 the same as the BBB) I see a clock and activity on MMC_DAT0.
But that is all I see. Indeed after about 8 seconds the whole power tree shuts down and then restarts about 1 second later.
Because I see activity on MMC0 if I have a card fitted and no activity when there is no card I am deducing that the RBL is at least starting. I have loaded my uSD card with the latest Debian image (Debian (BeagleBone, BeagleBone Black - 2GB SD) and this works fin in a BBB just not on my board.
Sysboot bits are set the same as BBB - should I be seeing something on UART0?
OK so some questions:
1) Is there any output I should expect to see from the RBL - UART0 debug messages etc etc.
2) What is causing the PSU to power cycle? is this RBL or some other mechanism?
3) is it (highly unlikely) that my board looks just fine but because ALL of my NV storage apart from the uSD card is blank that I am having an issue?
// further background
The hardware is for all intents and purposes the SAME as a BBB, but I have also added a front end Power supply, battery charger/coulomb counter a pair of displays, sound (looking very similar to the audio cape) and finally an keyboard. I would have just used BBBs onto a cape to provide this but mechanical constraints limit the available board height.
The PCB is impedance controlled and routed over 6 layers (I believe that I have followed all appropriate design considerations but feel free to check!)
/Andy
