I am using Toradex with Iris carrier board v1.1A
Computer on module ; Colibri IMX6DL v1.0A
I have tried connecting UART A or B channels an RF transceiver’s UART as
TxD to RxD
Rxd to TxD
I can send data to RF transceiver and RF transceiver transmits that data over air.
But RF transceiver can’t send data back to my toradex. I’ve watched TxD and RxD channels.
When My RF transceiver isn’t connected to Toradex or when it is connected to another device it’s TxD pin is normally working and sending data.
But when Toradex’s RxD pin connected to TxD pin of my transceiver that TxD pin cannot be grounded by my RF module. It switches between 3.3V and 2.8V so toradex can’t read it as a logic level.
Here i attached a photo. Blue color is TxD of RF modüle which is connected to RxD of Toradex which cannot be grounded while sending data.
The Iris carrier board does have TTL to RS232 transceivers on all UARTs.
When you want to connect a TTL level peripheral to those UARTs you have to disable the RS232 transceiver, otherwise both the RS232 transceiver and the RF transceiver will drive the RX pin.
The SODIMM_104 is driven by i.MX6 ball SD4_DATA0, the GPIO on that ball is GPIO2_IO08. This pin is already muxed in the device tree to have GPIO functionality.
So you can use the GPIO sysfs interface to control the GPIO from userspace.
e.g.