DS_1209F_004
73S1209F Data Sheet
Miscellaneous Control Register 0 (MISCtl0): 0xFFF1 Å 0x00
Transmit and receive (TX and RX) pin selection and loop back test configuration are set up via this register.
Table 37: The MISCtl0 Register
MSB
LSB
SLPBK SSEL
PWRDN
–
–
–
–
–
Bit
Symbol
Function
MISCtl0.7
MISCtl0.6
MISCtl0.5
MISCtl0.4
MISCtl0.3
MISCtl0.2
PWRDN
This bit places the 73S1209F into a power down state.
–
–
–
–
–
1 = UART loop back testing mode. The pins TXD and RXD are to be
connected together externally (with SLPBK =1) and therefore:
SLPBK SSEL
Mode
MISCtl0.1
SLPBK
0
0
1
1
0
1
0
1
normal using Serial_0
normal using Serial_1
Serial_0 TX feeds Serial_1 RX
Serial_1 TX feeds Serial_0 RX
Selects either Serial_1 if set =1 or Serial_0 if set = 0 to be connected
to RXD and TXD pins.
MISCtl0.0
SSEL
1.7.4.1 Serial Interface 0
The Serial Interface 0 can operate in four modes:
•
Mode 0
Pin RX serves as input and output. TX outputs the shift clock. Eight bits are transmitted with the LSB
first. The baud rate is fixed at 1/12 of the crystal frequency. Reception is initialized in Mode 0 by
setting the flags in S0CON as follows: RI0 = 0 and REN0 = 1. In other modes, a start bit when REN0
= 1 starts receiving serial data.
•
Mode 1
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 S0BUF, and stop bit sets the
flag RB80 in the Special Function Register S0CON. In mode 1 either internal baud rate generator or
timer 1 can be use to specify baud rate.
•
•
Mode 2
This mode is similar to Mode 1, with two differences. The baud rate is fixed at 1/32 or 1/64 of
oscillator frequency and 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 TB80 in S0CON is output as the 9th bit, and at receive, the 9th bit
affects RB80 in Special Function Register S0CON.
Mode 3
The only difference between Mode 2 and Mode 3 is that in Mode 3 either internal baud rate generator
or timer 1 can be use to specify baud rate.
The S0BUF register is used to read/write data to/from the serial 0 interface.
Rev. 1.2
41
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
