Hello,
I am trying to get UART4 working on a custom AM335x board and am having some trouble. It's using Linux and I can transmit data out from the board and receive it on my computer but cannot receive data sent out from my computer to the board. I verified with a scope that there is serial data making it to the UART4 RX pin. I also tried shorting the tx and rx pins together to form a loop in case this was some type of timing issue, but in either case I can not see my outgoing data echo back on /dev/ttyO4.
I added the following pin muxing configurations
{"mii1_txd3.uart4_rxd", OMAP_MUX_MODE3 | AM33XX_SLEWCTRL_SLOW |
AM33XX_PIN_INPUT_PULLUP},
{"mii1_txd2.uart4_txd", OMAP_MUX_MODE3 | AM33XX_PULL_UP |
AM33XX_PULL_DISA |
AM33XX_SLEWCTRL_SLOW},
and therefore had to add the uart4 to the mux entries because they were previously NULL:
_AM33XX_MUXENTRY(MII1_TXD3, 0,
"mii1_txd3", NULL, "rgmii1_td3", "uart4_rxd",
"mcasp1_fsx", "mmc2_dat1", "mcasp0_fsr", "gpio0_16"),
_AM33XX_MUXENTRY(MII1_TXD2, 0,
"mii1_txd2", NULL, "rgmii1_td2", "uart4_txd",
"mcasp1_axr0", "mmc2_dat2", "mcasp0_ahclkx", "gpio0_17"),\
Not sure what's going on, I don't think these pins are used elsewhere.
