Block descriptions

UM0805

14/29

Doc ID 16304 Rev 3

6.8

Real time clock (battery powered)

The real time clock (RTC) is powered with a 3V external battery (J9) in order to avoid losing

its data even if the main power supply is switched off.

6.9

General power supply

From a 12 V ~ 25 V external AC/DC regulator power source, this block generates all the

required voltages as follows:

●

1.0 V (Switching regulator) to supply the internal logic of the SPEAr600

●

1.2 V (Switching regulator) for the FPGA core

●

1.8 V (LDO regulator) for the DDR2 memory

●

2.5 V (LDO regulator) for the analog portion of SPEAr600 and for the Ethernet interface

●

3.3 V (LDO regulator) to supply the other interfaces

●

5 V (Switching regulator) to supply the USB Host VBUS

A power monitor is also present to provide the general reset of the board.

6.10

General-purpose I/Os

Ten general purpose I/Os are present on the board. Four of them are connected to a DIP

switch to allow the user to select/deselect them. The other two, GPIO4 and GPIO5, drive

two LEDs (one green and one yellow). All the GPIOs are also connected to the J19

connector which also has GND and 3.3V pins available.

Note:

For the connector pinout, refer to the schematic drawing available on www.st.com/spear.

6.11

LEDs

Several LEDs are present on the board. They display the following status information:

●

D13 (green) - Main power present

●

D1 (green) - VBUS present on USB HOST port 1

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D3 (green) - VBUS present on USB HOST port 1

●

D2 (red) - Abnormal current flowing on USB HOST 1 port

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D4 (red) - Abnormal current flowing on USB HOST 1 port

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D5 (yellow) - Switched on/off by GPIO4

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D6 (green) - Switched on/off by GPIO5

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D7-11 (yellow) - Ethernet line status LEDs. Refer to Section 6.4: Ethernet subsystem.