SN32F760 Series
32-Bit Cortex-M0 Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 156
Version 2.0
14.5.4 RS485/EIA-485 DRIVER DELAY TIME
The driver delay time is the delay between the last stop bit leaving the TXFIFO and the de-assertion of URTS. This
delay time can be programmed in the 8-bit
register. The delay time is in periods of the baud
clock. Any delay time from 0 to 255 bit times may be used.
14.5.5 RS485/EIA-485 OUTPUT INVERSION
The polarity of the direction control signal on the URTS pin can be reversed by programming OINV bit in
register. When OINV bit is set, the direction control pin will be driven to logic 1 (driven LOW)
when the transmitter has data waiting to be sent. The direction control pin will be driven to logic 0 (driven High) once
the last bit of data has been transmitted.
14.5.6 RS485/EIA-485 FRAME STRUCTURE
SN32Fxxx
URXD
UTXD
URTS
RS-485 TRANSCEIVER
Differential Bus
bit0
bit1
bit2
bit3
bit4
bit5
bit6
Start
bit7
Parity
Stop
UTXD
URTS
14.6 BAUD RATE CALCULATION
The USART baud rate is calculated as:
USARTn_PCLK
UART
BAUDRATE
=
Oversampling x (256 x DLM + DLL) x (1 + DIVADDVAL / MULVAL)
Where USARTn_PCLK is the peripheral clock,
and
are the standard UART baud rate
divider registers, and DIVADDVAL and MULVAL are USART fractional baud rate generator specific parameters in
The value of MULVAL and DIVADDVAL should comply with the following conditions:
1. 1
≤ MULVAL ≤ 15
2. 0
≤ DIVADDVAL ≤ 14
3. DIVADDVAL< MULVAL
4. Oversampling is 8 or 16