Using the ATEVK525
2-12
ATEVK525 Mass Storage Board for AVR
7740B–AVR–03/08
2.4
LEDs
Three LEDs are on the board:
–
PWR_FAIL
: orange LED that signals an overvoltage condition if the protection
circuit is mounted. This LED is optional.
–
WRITE
: red LED connected to PORTD7 of micro (also LED1 on STK525), that
may be driven by software when initiating a SCSI Write command
–
READ
: green LED connected to PORTD5 of micro (also LED3 on STK525),
that may be driven by software when initiating a SCSI Read command
Figure 2-7 .
On-board SCSI signalling LEDs
2.5
Test Points
Several test points are included on the board to facilitate debug during development. All
the test points are circular pads with a silk-screen printing that indicates the
corresponding signal:
– VCC: power supply voltage (should be 3.3V), taken after the power protection
circuit
– GND: power supply ground
– SD_MISO: SD/MMC card MISO signal (card output)
– SD_MOSI: SD/MMC card MOSI signal (card input)
– SD_SCK: SD/MMC clock signal
– SD_CS: SD/MMC chip select signal (active low)
– NF_CLE: NAND Flash CLE signal
– NF_ALE: NAND Flash ALE signal
– NF_RE: NAND Flash RE# signal
– NF_WE: NAND Flash WE# signal