Receive Clock Mode Source Bit (Rcm) Sccr Bit 14; Figure 8-7 Sci Baud Rate Generator; Table 8-2 Tcm And Rcm Bit Configuration - Motorola DSP56305 User Manual

8.3.3.4

Receive Clock Mode Source Bit (RCM) SCCR Bit 14

RCM selects whether an internal or external clock is used for the receiver. If RCM is
cleared, the internal clock is used. If RCM is set, the external clock (from the SCLK
signal) is used. Hardware and software reset clear RCM.
TCM RCM TX Clock
0 0 Internal
0 1 Internal
1 0 External
1 1 External
F
core
Divide
By 2
Divide
By 16
Timer
Interrupt
(STMINT)
BPS =
64 × (7 × SCP + 1) × CD + 1)
where: SCP = 0 or 1
CD = $000 to $FFF
MOTOROLA

Table 8-2 TCM and RCM Bit Configuration

RX Clock
Internal
External
Internal
External
12-bit Counter
CD11–CD0
F
core

Figure 8-7 SCI Baud Rate Generator

DSP56305 User's Manual
Serial Communication Interface (SCI)
SCLK
Signal
Output Synchronous/Asynchronous
Input Asynchronous Only
Input Asynchronous Only
Input Synchronous/Asynchronous
Prescaler:
Divide by
1 or 8
SCP
SCI Core Logic
Uses Divide by 16 for
Asynchronous
Uses Divide by 2 for
Synchronous
COD
SCKP
SCI Programming Model
Mode
Divide
By 2
Internal Clock
If Asynchronous
Divide by 1 or 16
If Synchronous
Divide By 2
SCKP = 0 +
SCKP = 1 –
TO SCLK
AA0693
8-19