Product Specs

Table Of Contents
35 UARTE Universal asynchronous receiver/
transmitter with EasyDMA
Page
337
The STOPTX and STOPRX tasks may not be always needed (the peripheral might already be stopped),
but if STOPTX and/or STOPRX is sent, software shall wait until the TXSTOPPED and/or RXTO event is
received in response, before disabling the peripheral through the ENABLE register.
35.9 Pin configuration
The different signals RXD, CTS (Clear To Send, active low), RTS (Request To Send, active low), and TXD
associated with the UARTE are mapped to physical pins according to the configuration specified in the
PSEL.RXD, PSEL.CTS, PSEL.RTS, and PSEL.TXD registers respectively.
The PSEL.RXD, PSEL.CTS, PSEL.RTS, and PSEL.TXD registers and their configurations are only used
as long as the UARTE is enabled, and retained only for the duration the device is in ON mode. PSEL.RXD,
PSEL.RTS, PSEL.RTS and PSEL.TXD must only be configured when the UARTE is disabled.
To secure correct signal levels on the pins by the UARTE when the system is in OFF mode, the pins must be
configured in the GPIO peripheral as described in Table 80: GPIO configuration before enabling peripheral
on page 337.
Only one peripheral can be assigned to drive a particular GPIO pin at a time. Failing to do so may result in
unpredictable behavior.
Table 80: GPIO configuration before enabling peripheral
UARTE signal
UARTE pin
Direction
Output value
RXD
As specified in PSEL.RXD
Input
Not applicable
CTS
As specified in PSEL.CTS
Input
Not applicable
RTS
As specified in PSEL.RTS
Output
1
TXD
As specified in PSEL.TXD
Output
1
35.10 Registers
Table 81: Instances
Base address
Peripheral
Instance
Description
Configuration
0x40002000
UARTE
UARTE0
Universal Asynchronous Receiver/
Transmitter with EasyDMA
Table 82: Register Overview
Register
Offset
Description
TASKS_STARTRX
0x000
Start UART receiver
TASKS_STOPRX
0x004
Stop UART receiver
TASKS_STARTTX
0x008
Start UART transmitter
TASKS_STOPTX
0x00C
Stop UART transmitter
TASKS_FLUSHRX
0x02C
Flush RX FIFO into RX buffer
EVENTS_CTS
0x100
CTS is activated (set low). Clear To Send.
EVENTS_NCTS
0x104
CTS is deactivated (set high). Not Clear To Send.
EVENTS_RXDRDY
0x108
Data received in RXD (but potentially not yet transferred to Data RAM)
EVENTS_ENDRX
0x110
Receive buffer is filled up
EVENTS_TXDRDY
0x11C
Data sent from TXD
EVENTS_ENDTX
0x120
Last TX byte transmitted
EVENTS_ERROR
0x124
Error detected
EVENTS_RXTO
0x144
Receiver timeout
EVENTS_RXSTARTED
0x14C
UART receiver has started
EVENTS_TXSTARTED
0x150
UART transmitter has started
EVENTS_TXSTOPPED
0x158
Transmitter stopped
SHORTS
0x200
Shortcut register
INTEN
0x300
Enable or disable interrupt
INTENSET
0x304
Enable interrupt
INTENCLR
0x308
Disable interrupt