Intel PXA27x Series, User Manual

Page: 39 / 88

Intel
®
PXA27x Processor Developer’s Kit - User’s Guide 39
2.3.1 Power
When reading this section, refer to the daughter card schematic diagram.
2.3.1.1 Power Sources
The Intel
®
PXA270 Processor can derive power from any of the sources described in Table 6 .
2.3.2 SRAM
The daughter card provides 2 Mbytes of static random-access memory in addition to the SRAM
integrated into the daughter card. This low-power SRAM, with relatively slow access time (70 ns),
is representative of the type typically found in low-power devices. The card-level SRAM maps to
the upper half of
the Processor chip select nCS2.
2.3.3 Programmable Daughter Card Logic (CPLD1)
A Xilinx complex programmable logic device (CPLD) contains the logic for controlling the
daughter card memory-bus transceiver’s JTAG chaining and MSL/PCMCIA signal mixing. This
device can interface with two signaling-voltage levels.
For information on programming CPLD1, see Section 3.6, “Programming Flash Memory and
Logic Devices” on page 85 .
2.3.4 Stand-Alone I/O Interface
When the daughter card operates in stand-alone mode, the RS-232 serial port (see Section 2.3.5 )
provides the interface to a host computer or other serial device at speeds up to 115 kbps. The JTAG
interface (see
Section 2.3.6 ) provides debugging and software downloading.
2.3.5 Full-Featured RS-232 Serial Port
The Intel
®
PXA270 Processor Full-Featured UART controller connects to a standard DB-9
connector via a Maxim RS-232 transceiver. For programming details, see the FFUART chapter in
the
Intel
®
PXA27x Processor Family Developer’s Manual .
Table 6. Power Sources on the Intel
®
PXA27x Processor Developer’s Kit Daughter Card
Source
Connector
or
Component
Description
main board J22
To power the Intel
®
PXA270 Processor from the main board, install jumpers
on J22 between pins 1 and 3, and between pins 2 and 4 (see the Intel
®
PXA270 Processor schematic diagram). This is the default setting for J22.
The default main board supply voltage is 5V.
Ex5 VDC J23
To power the Intel
®
PXA270 Processor from an external power supply:
1. CAUTION: Turn off the main board power and remove the Intel
®
PXA270 Processor from the main board.
2. Connect a 5-volt, 2-amp source to J23.