Datasheet
DS_1215F_003 73S1215F Data Sheet
Rev. 1.4 43
Serial Interface 0 Control Register (S0CON): 0x9B Å 0x00
Transmit and receive data are transferred via this register.
Table 39: The S0CON Register
MSB LSB
SM0 SM1 SM20 REN0 TB80 RB80 TI0 RI0
Bit Symbol Function
S0CON.7 SM0 These two bits set the UART0 mode:
Mode Description SM0 SM1
0 N/A 0 0
1 8-bit UART 0 1
2 9-bit UART 1 0
3 9-bit UART 1 1
S0CON.6 SM1
S0CON.5 SM20 Enables the inter-processor communication feature.
S0CON.4 REN0 If set, enables serial reception. Cleared by software to disable reception.
S0CON.3 TB80 The 9
th
transmitted data bit in Modes 2 and 3. Set or cleared by the MPU,
depending on the function it performs (parity check, multiprocessor
communication etc.).
S0CON.2 RB80 In Modes 2 and 3 it is the 9th data bit received. In Mode 1, if SM20 is 0,
RB80 is the stop bit. In Mode 0 this bit is not used. Must be cleared by
software.
S0CON.1 TI0 Transmit interrupt flag, set by hardware after completion of a serial transfer.
Must be cleared by software.
S0CON.0 RI0 Receive interrupt flag, set by hardware after completion of a serial
reception. Must be cleared by software.
1.7.4.2 Serial Interface 1
The Serial Interface 1 can operate in 2 modes:
• Mode A
This mode is similar to Mode 2 and 3 of Serial interface 0, 11 bits are transmitted or received: a start
bit (0), 8 data bits (LSB first), a programmable 9th bit, and a stop bit (1). The 9th bit can be used to
control the parity of the serial interface: at transmission, bit TB81 in S1CON is outputted as the 9th
bit, and at receive, the 9th bit affects RB81 in Special Function Register S1CON. The only difference
between Mode 3 and A is that in Mode A only the internal baud rate generator can be use to specify
baud rate.
• Mode B
This mode is similar to Mode 1 of Serial interface 0. Pin RX serves as input, and TX serves as serial
output. No external shift clock is used, 10 bits are transmitted: a start bit (always 0), 8 data bits (LSB
first), and a stop bit (always 1). On receive, a start bit synchronizes the transmission, 8 data bits are
available by reading S1BUF, and stop bit sets the flag RB81 in the Special Function Register
S1CON. In mode 1, the internal baud rate generator is use to specify the baud rate.
The S1BUF register is used to read/write data to/from the serial 1 interface.