Texas Instruments TMS320C3x - Manual (Page 424)

Serial Ports
12-45 Peripherals
12.2.14.3 DMA Transfer With Serial Port Interrupt
Example 12–8 and Example 12–9 of Section 12.3.11 on page 12-74 use the
DMA synchronized to serial port interrupts to transfer data (128 words) from
an array buffer to the serial port0 output register.
12.2.14.4 Serial Analog Interface Chips Interface Example
The TLC320C4x analog interface chips (AIC) from Texas Instruments offer a
zero-glue-logic interface to the ’C3x family of DSPs. The interface is shown in
Figure 12–33 as an example of the ’C3x serial-port configuration and operation.
Figure 12–33. TMS320C3x Zero-Glue-Logic Interface to TLC320C4x Example
XF0
CLKR0
CLKX0
FSR0
DR0
FSX0
DX0
TCLK0
RESET
SCLK
FSR
DR
FSX
DX
MCLK
TMS320C3x TLC320C4x
WORD
OUT+
OUT–
IN+
IN–
VCC
Analog
Out
Analog
In
GND
The ’C3x resets the AIC through the external pin XF0. It also generates the
master clock for the AIC through the timer 0 output pin, TCLK0. (Precise selec-
tion of a sample rate may require the use of an external oscillator rather than
the TCLK0 output to drive the AIC MCLK input.) In turn, the AIC generates the
CLKR0 and CLKX0 shift clocks as well as the FSR0 and FSX0 frame synchro-
nization signals.
A typical use of the AIC requires an 8-kHz sample rate of the analog signal.
If the clock input frequency to the ’C3x device is 30 MHz, you should load the
following values into the serial port and timer registers.
Serial Port:
Port global-control register
0E970300h
FSX/DX/CLKX port-control register 00000111h
FSR/DR/CLKR port-control register 00000111h
Timer:
Timer global-control register
000002C1h
Timer-period register 00000001h