Texas Instruments TMS320C3x - Manual (Page 420)

Serial Ports
12-41 Peripherals
Figure 12–32. Variable Continuous Mode Without Frame Sync
CLKX/R
FSR/FSX (external)
FSX (internal)
DX/DR A1 AN B1 BN C1 C2
XINT
RINT
Load DXR with D
read DRR
Set
R/XFS
M
DXR loaded
with B
XINT
DXR loaded
with A
XINT
RINT
Load DXR with C
read DRR
R/XVAREN = 1
R/XFSM = 1
12.2.13 Serial-Port Initialization/Reconfiguration
The serial ports are controlled through memory-mapped registers on the dedi-
cated peripheral bus. A general procedure for initializing and/or reconfiguring
the serial ports follows.
1) Halt the serial port by clearing the XRESET and/or RRESET bits of the serial-
port global-control register. To do this, write a 0 to the serial-port global-
control register. The serial ports are halted on RESET.
2) Configure the serial port via the serial-port global-control register (with
XRESET = RRESET = 0) and the FSX/DX/CLKX and FSR/DR/CLKR port-
control registers. If necessary, configure the receive/transmit registers;
timer control (with XHLD = RHLD = 0), timer counter, and timer period.
Refer to section 12.2.14 for more information.
3) Start the serial-port operation by setting the XRESET and RRESET bits
of the serial-port global-control register and the XHLD and RHLD bits of
the serial-port receive/transmit timer-control register, if necessary.
12.2.14 TMS320C3x Serial-Port Interface Examples
In addition to the examples presented in this section, you can find DMA/serial
port initialization examples in Example 12–9 and Example 12–10 on pages
12-76 and 12-77, respectively.