10.3 UART Interface

The ATWINC3400-MR210xA supports the Universal Asynchronous Receiver/Transmitter (UART) interface. Wi-Fi and Bluetooth Low Energy interfaces must be used for debug purposes only. Wi-Fi UART pins are available on pins 16 (TXD) and 17 (RXD). Bluetooth Low Energy UART pins are available on pins 8 (TXD) and 9 (RXD). The UART is compatible with the RS-232 standard.

The default configuration for accessing the Wi-Fi UART interface of the ATWINC3400-MR210xA is mentioned below:
  • Baud rate: 460800
  • Data: 8-bit
  • Parity: None
  • Stop bit: 1-bit
  • Flow control: None

It also has RX and TX FIFOs, which ensure reliable high-speed reception and low software overhead transmission. FIFO size is 4 x 8 for both RX and TX direction. The UART also has status registers showing the number of received characters available in the FIFO and various error conditions, as well as, the ability to generate interrupts based on these status bits.

An example of the UART receiving or transmitting a single packet is shown in the following figure. This example shows 7-bit data (0x45), odd parity and two stop bits.

Figure 10-4. Example of UART RX of TX Packet