UART

cyhal_uart_impl_features

The CAT4 UART supports the following features:

• Data bits: 8
• Stop bits: 1 or 2
• Parity: Even, odd, or none
• FIFO Depth: 64

On CAT4 devices, there are three types of UART: Fast, Debug (also referred to as "Slow") and SECI (also referred to as GCI). There are slight differences in functionality between the three:

• Only the Fast UART supports flow control
• The Fast UART can be driven by either the ALP clock or the dedicated "Fast UART" clock. The other UARTs can only be driven by the ALP clock.
• The Debug UART does not support setting arbitrary RX FIFO trigger levels. The level must be one of: 2, 1/4 full + 1, 1/2 full + 1, or full - 1.
• The Debug UART does not support TX FIFO trigger level interrupts (but it does support the "TX Empty" event)

The following events are supported:

• CYHAL_UART_IRQ_TX_TRANSMIT_IN_FIFO
• CYHAL_UART_IRQ_RX_DONE
• CYHAL_UART_IRQ_TX_FIFO (except Debug UART)
• CYHAL_UART_IRQ_TX_EMPTY (Debug UART only)
• CYHAL_UART_IRQ_RX_FIFO

See the device datasheet for information about which UARTs can connect to which pins.