SODIMM Pin 53 ...
Added by Thomas Catalino over 12 years ago
(Posted on behalf of a customer)
The datasheet for the MITYDSP-L138F shows Pin 53 as reserved, however the Industrial IO board uses it for SPI1_SCS0. Why does the datasheet show it as reserved?
Replies (1)
RE: SODIMM Pin 53 ... - Added by Michael Williamson over 12 years ago
SPI1_SCS0 is indeed connected to that pin on the module. It is also connected to the chip-select on the on-board SPI NOR FLASH, which is used for loading the first stage bootloader (UBL) as well as u-Boot. The pin was brought out to the edge connector in order to facilitate factory level programming while holding the CPU in reset. It's really not available for general purpose use as asserting it externally would interfere with the boot process, and it cannot be used as an external SPI chip select because it's already allocated for use on the module. This is why it is marked as "reserved" on the data sheet.
The industrial I/O board does route that signal to an expansion connector header, but in fairness it's not very a usable connection. Sorry for the confusion.
-Mike
