Am 30.01.2015 um 01:57 schrieb Grazvydas Ignotas notasas@gmail.com:
Hi,
On Thu, Jan 29, 2015 at 5:27 PM, Dr. H. Nikolaus Schaller hns@goldelico.com wrote:
PS: I am in the middle of placing the copper traces for the CPU board. Looks as if it is just time-consuming, but no big hurdles are visible. It is indeed easier on a 8-layer 100um structure PCB with micro-vias than a 4-layer board without and 150um structure (making it much cheaper…). With a little luck we will have our own omap5 board soon (there can be an engineering variant with 2 SD slots and a micro-USB socket for external power and FTDI console - I plan to build 1, maybe 2 of these for board bringup)
Aren't we going to have some UART-to-USB solution on the charging port on final boards too?
Yes, for complete devices. This optional addition allows to operate the CPU baord without main board (or some breakout board).
It is needed for board-bringup for two reasons: * the production device will use a different UART3 pinmux, i.e. we will have to recompile MLO first, before I can debug the board. With the debug addition, the SD card from the EVM should work out of the box * the other thing is that the CPU is sandwiched between its PCB and the main PCB, i.e. I have no access to any measurement points - or I have no console. Therefore I need a way to operate it without main board.
As soon as the CPU board works, we can switch to the different MLO and there is no need to worry about that interim solution any more.
BR, Nikolaus