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M0A21/M0A23 Series
May 06, 2022
Page
433
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
logic status.
RTSACTLV = 0
nRTS Signal
(internal signal)
Active
Byte(i)
Byte (i +n)
Start
bit
RX pin input
( from external)
nRTS inactive
delay
External
delay
Start
bit
The Bytes
Number Stored
In FIFO
<
The Bytes Number
Stored In FIFO
=
nRTS pin output status of UART function mode, nRTS auto - flow control enabled
RTSTRGLV
(UART_FIFO[19:16])
RTSTRGLV
(UART_FIFO[19:16])
RTSSTS
(UART_MODEM[13])
nRTS pin output
RTSACTLV = 1
(Default)
Figure 6.11-13 UART nRTS Auto-Flow Control Enabled
As shown in Figure 6.11-14, in software mode (ATORTSEN (UART_INTEN[12])=0), the nRTS flow is
directly controlled by software programming of RTS (UART_MODEM[1]) control bit.
Setting RTSACTLV (UART_MODEM[9]) can control the nRTS pin output is inverse or non-inverse from
RTS (UART_MODEM[1]) control bit. User can read the RTSSTS (UART_MODEM[13]) bit to get real
nRTS pin output voltage logic status.
Active
nRTS pin output status of UART function mode
(default)
RTS control bit
(UART_MODEM[1])
Set UART_MODEM[1]=0
Set UART_MODEM[1]=1 by software
RTSSTS
(UART_MODEM[13])
nRTS pin output
RTSACTLV=0
RTSACTLV=1
Figure 6.11-14 UART nRTS Auto-Flow with Software Control
6.11.5.9 IrDA Function Mode
The UART controller also provides Serial IrDA (SIR, Serial Infrared) function (Setting
UART_FUNCSEL[2:0] to
‘010’ to enable the IrDA function). The SIR specification defines a short-range
infrared asynchronous serial transmission mode with one start bit, 8 data bits, and 1 stop bit. The
maximum data rate is 115.2 kbps. The IrDA SIR block contains an IrDA SIR protocol encoder/decoder.
The IrDA SIR protocol is half-duplex only. So, it cannot transmit and receive data at the same time. The
IrDA SIR physical layer specifies a minimum 10 ms transfer delay between transmission and reception,
and this delay feature must be implemented by software.
In IrDA mode, the BAUDM1 (UART_BAUD[29]) must be cleared.