FSG
(Needs resynchronization)
CLKG
resynchronize)
(No need to
CLKG
(FSRP=1)
FSR external
(FSRP=0)
FSR external
CLKR
CLKR
Figure 15-20. CLKG Synchronization and FSG Generation When GSYNC = 1 and CLKGDV = 3
15.3.4 Reset and Initialization Procedure for the Sample Rate Generator
To reset and initialize the sample rate generator:
1. Place the McBSP/sample rate generator in reset.
During a DSP reset, the sample rate generator, the receiver, and the transmitter reset bits (GRST, RRST,
and XRST) are automatically forced to 0. Otherwise, during normal operation, the sample rate generator can
be reset by making GRST = 0 in SPCR2, provided that CLKG and/or FSG is not used by any portion of the
McBSP. Depending on your system you may also want to reset the receiver (RRST = 0 in SPCR1) and reset
the transmitter (XRST = 0 in SPCR2).
If GRST = 0 due to a device reset, CLKG is driven by the CPU clock divided by 2, and FSG is driven
inactive-low. If GRST = 0 due to program code, CLKG and FSG are driven low (inactive).
2. Program the registers that affect the sample rate generator.
Program the sample rate generator registers (SRGR1 and SRGR2) as required for your application. If
necessary, other control registers can be loaded with desired values, provided the respective portion of the
McBSP (the receiver or transmitter) is in reset.
After the sample rate generator registers are programmed, wait 2 CLKSRG cycles. This ensures proper
synchronization internally.
3. Enable the sample rate generator (take it out of reset).
In SPCR2, make GRST = 1 to enable the sample rate generator.
After the sample rate generator is enabled, wait two CLKG cycles for the sample rate generator logic to
stabilize.
On the next rising edge of CLKSRG, CLKG transitions to 1 and starts clocking with a frequency equal to
CLKG frequency
+
Input clock frequency
(CLKGDV
)
1)
(13)
where the input clock is selected with the SCLKME bit of PCR and the CLKSM bit of SRGR2 in one of the
configurations shown in
4. If necessary, enable the receiver and the transmitter.
If necessary, remove the receiver and transmitter from reset by setting RRST and/or XRST = 1.
Multichannel Buffered Serial Port (McBSP)
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
895
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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