SMART Embedded Computing RTM-ATCA-F140 Series, Инструкция по установке и использованию

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Functional Description
RTM-ATCA-F140 Series Installation and Use (6806800M97M) 55
The LEDs are controlled by a PCF8574-type I
2
C parallel I/O expander. The ports of this are
connected as shown below.
The I/O expander interrupt line is not connected.
For the red, green, and amber LEDs the cathodes are connected directly to the I/O
expander pins. The anodes are connected to the management 3.3V supply through current
limiting resistors selected to limit the LED current to 15mA. Since the I/Os power up in the
high state, this ensures that the LEDs remain off until explicitly turned on by the IPMC.
For the blue LED an external FET inverter is used to ensure the LED is on at power-up. A
charge pump is used to provide adequate forward voltage if the LED cannot be operated
directly from 3.3V.
The I/O expander resides at I
2
C address 0x40.
4.2.4 I
2
C Address Map
The next table summarizes the I
2
C address assignments.
Table 4-2 PCF 8574 Port Usage
Port Direction Connection
0 Output H/S LED (Blue)
1 Output OOS LED (Red)
2 Output IS LED (Green)
3 Output ATTN LED (Amber)
4 Output OOS LED (Amber)
5 Output FPGA PROM select
6 N/A (not connected)
7 Input FPGA DONE
Table 4-3 I
2
C Bus Address Map
Address Device
0x40 I/O Expander (LED control)
0x90 Temperature sensor (top)
0x92 Temperature sensor (middle)
0x94 Temperature sensor (bottom)
0xA0 Serial EEPROM