Nations Technologies Inc.
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Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
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CTS (Clear To Send):
When transmitter detects that CTS is valid (low level), the next data is sent.
RTS (Request To Send):
When receiver is ready to receive new data, pull the RTS pin low.
LPUART has the following characteristics:
Idle status without sending or receiving
A start bit
A data word (8 bits) with the least significant bits first
A stop bit, indicating the end of a data frame
A status register (LPUART_STS)
Data register (LPUART_DAT)
Two baud rate configuration registers (LPUART_BRCFG1 and LPUART_BRCFG2) using fractional baud rate
generators:16-bit integer and 8-bit decimal representations
For specific definitions of each bit in the registers above, please refer to Section 23.6 of register Description.
LPUART frame format
The LPUART data word length is fixed at 8 bits (see Figure 23-2). During the start bit, TX pin is at a low level and
during the stop bit it is at a high level. The parity bit follows the data word when enabled.
Both sending and receiving are driven by two different baud clock generators. When the LPUART_CTRL.TXEN of
transmitter is set, the corresponding baud clock generator generates baud clock. When the start bit is received, the
receiver's corresponding baud clock generator generates the clock.
Figure 23-2 Frame format
Note: in this chapter, unless special instruction, setting means that a register is set to state '1', and resetting or
clearing means that a register is set to state '0'. Hardware or programs may set or clear a register. Please refer to
this chapter for details.
Transmitter
When the Transmit Enable bit (LPUART_CTRL.TXEN) is set and there is data in the buffer, the transmitter sends 8-
bit data words. The data in the shift register is output on the TX pin.
8-bit word length, 1 stop bit
Next data frame
Start
bit
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Stop
bit
Data frame
Possible
parity bit
start
bit
Note:If there is no parity bit, the stop bit is after bit 7