User`s manual

Am186™CC Microcontroller Router Reference Design User’s Manual
2-16
Three LEDs (CR1–CR3 at location K-9) provide status information for the Ethernet
port. The function of these LEDs is controlled by the ISA bus configuration
registers on the PCnet-ISA II Ethernet controller and can be modified through
software or the EEPROM. The default functions of the LEDs are shown in
Table 2-8.
The default configuration of the Am186CC microcontroller router reference design
uses DRAM as main system memory and the 64K x 16 SRAM as the Ethernet
packet memory. In this configuration, the DRAM resides in the lower 512 Kbytes
of memory space from 00000–7FFFFh, and the 128 Kbytes of Ethernet packet
SRAM use MCS0
space located from 80000–9FFFFh. The space the SRAM
resides in can be moved from 00000h up to FFFFFh in increments equal to the
SRAM block size. There is no fixed location for the SRAM as it is chosen by the
programmer.
Table 2-7. RJ-45 Connector Pin Functions
Pin Number Function
1TX+
2TX–
3RX+
4 Not used
5 Not used
6RX–
7 Not used
8 Not used
Table 2-8. PCnet-ISA II Ethernet Controller LED Status Information
LED Ethernet Controller
Signal Name
LED Function
CR1 LED0 Indicates a good 10BaseT connection.
CR2 LED1 Indicates receive activity from the network.
CR3 LED3 Indicates transmit activity from the network.
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