Intel PXA250 and PXA210 manual Introduction, 3. Signal Pin Descriptions Sheet 7 of

Introduction

Table 1-3. Signal Pin Descriptions (Sheet 7 of 7)

Name	Type	Description
VSSN	SUP	Ground supply for memory bus and PCMCIA pins. Connect these pins to the common
		ground plane on the PCB.
		Backup battery connection. Connect this pin to the backup battery supply. If a backup
BATT_VCC	SUP	battery is not required then this pin may be connected to the common 3.3v supply on
		the PCB.

NOTES:

1.Not pinned out for the PXA210 applications processor.

2.GPIO Reset Operation: After any reset, these pins are configured as GPIO inputs by default. The input buffers for these pins are disabled to prevent current drain and must be enabled prior to use by clearing the Read Disable Hold (RDH) bit.

To use a GPIO pin as an alternate function, follow this sequence:

1)Program the pin to the desired direction (input or output) using the GPIO Pin Direction Registers (GPDR).

2)Enable the input buffer by clearing the RDH bit, described above.

3)If needed, select the desired alternate function by programming the proper bits in the GPIO Alternate Function Register (GAFR).

1-10 PXA250 and PXA210 Applications Processors Design Guide