PCB prototypes and flash SPI testing

Posted on 4 October 2011 in Hardware by xilun

various bits of low level software, preparing the production of the first prototypes, validating some hardware subsystems and doing all sort of hardware + low level software debugging.

We are starting again to have things interesting to show, with some cute photos.

PCB prototypes

We recently received our first PCB prototypes for our motherboard:

XIOH motherboard

To prepare for testing the first assembled prototypes, we wanted to somehow test the communication between the EP80579 and the SPI flash. For now we have a 74LVC125A buffer between the two chips in order to isolate the flash from the SoC, and we wanted to validate this design.

We previously did a small model of the flash subsystem, A few days ago I heavily hacked it to make it work. (Well some of the modifications were probably not really necessary, but now we have a perfect signal quality :)

Heavily hacked flash prototype

The next step was to do the same test, this time using one of our spare naked PCBs dedicated to that kind of testing.We first soldered the flash and the buffer, then we strapped a HE10 ISP header to replace the EP80579 SPI drivers by a flash programmer (this is obviously not a perfect replacement, but we can't do much better...)

Here is a photo of the header being soldered:

Soldering an SPI header at SoC

Here is the soldered result, connected to the programmer:

Testing flash

And here is the result:

SPI flash communication test

So we are now hopeful that at least the SPI flash communication will work on our assembled board \\o/