ST72T311 ST Microelectronics, ST72T311 Datasheet - Page 62

• Manufacturer Part Number: ST72T311
• Description: 8-BIT MCU WITH 8 TO 16K OTP/EPROM
• Manufacturer: ST Microelectronics

ST72E311 ST72T311
SERIAL COMMUNICATIONS INTERFACE (Cont’d)
DATA REGISTER (DR)
Read/Write
Reset Value: Undefined
Contains the Received or Transmitted data char-
acter, depending on whether it is read from or writ-
ten to.
The Data register performs a double function (read
and write) since it is composed of two registers,
one for transmission (TDR) and one for reception
(RDR).
The TDR register provides the parallel interface
between the internal bus and the output shift reg-
ister (see Figure 34).
The RDR register provides the parallel interface
between the input shift register and the internal
bus (see Figure 34).
BAUD RATE REGISTER (BRR)
Read/Write
Reset Value: 00xx xxxx (XXh)
Bit 7:6= SCP[1:0] First SCI Prescaler
These 2 prescaling bits allow several standard
clock division ranges:
62/100
SCP1
DR7
7
7
PR Prescaling factor
62
SCP0
DR6
13
SCT2
1
3
4
DR5
SCT1
DR4
SCT0
DR3
SCP1
SCR2
DR2
0
0
1
1
SCR1 SCR0
DR1
SCP0
0
1
0
1
DR0
0
0
Bit 5:3 = SCT[2:0] SCI Transmitter rate divisor
These 3 bits, in conjunction with the SCP1 & SCP0
bits define the total division applied to the bus
clock to yield the transmit rate clock in convention-
al Baud Rate Generator mode.
Note: this TR factor is used only when the ETPR
fine tuning factor is equal to 00h; otherwise, TR is
replaced by the ETPR dividing factor.
Bit 2:0 = SCR[2:0] SCI Receiver rate divisor.
These 3 bits, in conjunction with the SCP1 & SCP0
bits define the total division applied to the bus
clock to yield the receive rate clock in conventional
Baud Rate Generator mode.
Note: this RR factor is used only when the ERPR
fine tuning factor is equal to 00h; otherwise, RR is
replaced by the ERPR dividing factor.
RR dividi ng factor
TR dividi ng factor
128
128
16
32
64
16
32
64
1
2
4
8
1
2
4
8
SCT2
SCR2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
SCR1
SCT1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
SCR0
SCT0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1