Using Ethernet port for alternate functionality

[pavangidaveer]

Hello,

In mpc5200B, we have configured Ethernet port (bit 12:15) of GPS PORT Configuration Register (MBAR + 0B00h) as 1010 (i,e. Two UARTes, J1850).

While in this configuration, we are not using ETH_8, ETH_15 & ETH_16 pins for its specified functionality i.e, UART5e_CD, UART4_CTS & UART4_CD respectively. Rather, we want to use these pins as GPIO, i.e, we want to read and write from/to these pins as in GPIO configuration without configuring Ethernet port (bit 12:15) of GPS PORT Configuration Register (MBAR + 0B00h) as 0000 (i.e, GPIO).

Could you please suggest us the method to achieve that?

[Pavel · Accepted solution]

If the MPC5200B Ethernet is configured using the GPS PORT Configuration Register (MBAR 0B00h) as 1010, the ETH8 is UART5e_CD, the ETH15 is UART4_CTS and ETH16 is UART4_CD signals. These pins cannot be uses as GPIO for this configuration. See the Figure 2-9 of the MPC5200B User's Manual.

You can use CD (carrier detect) signals as GPIO inputs using Input Port Change Register. See the Table 15-13 of the MPC5200B Reference Manual.

Have a great day,
Pavel Chubakov

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