Content originally posted in LPCWare by Rob65 on Sun May 22 22:46:04 MST 2011
Quote: jstratmann
The 'A' jumper was also a problem for me to get this example running. The documentation pg 37 drawing 38 is not clear, two jumpers are drawn red so you think that's it, but the A jumper pos is not shown.
It is a good thing to check the schematics also, there it is even more clear that J55 is a 3-position jumper block. Since the user manual only shows red jumpers on B and INH it follows that the A jumper should be removed.
Only the jumpers marked in red should be inserted, other jumpers in the jumper block described should be removed.
I've been using different boards from EA, some were given to me even before the user manual was available, so I am user to check the schematics for jumper configs.
This is a good thing to do - even with the UM at hand.
You can search the PDF file for e.g. PIO0_8, which is the MISO (Master In, Slave Out) pin of the SPI interface. You will discover that this pin is not only connected to J39 and the SD card connector but also to J38 (SPI Flash), J41 (7-segment LED) and J50 (I2C/SPI UART). The genuine SPI devices all have a tri-state output pin connected to MISO but the shift register at the 7-segment LED does not - so never connect 1-2 on J41 when using any other device.
Yes - this is stated in the user manual, but who is gonna check the 7-segment LED section of the manual while using SD, SPI Flash or anything else.
EA used a 4052 multiplexer (U26) to connect PIO1_11 to the SSEL lines of the different SPI blocks. Good thing is that they have jumpers on most pins so I made some jumper wires that I can insert between J39-2 and PIO3_0 etc. - having a few of those wires (with single female connectors at both ends) makes the board even more versatile.
The SPI UART already has its own SSEL pin (PIO2_8) so you can use one of the other 3 peripherals plus the SPI uart together :)
Rob