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Divider
/1... /4096
AUXCLK
1
0
1
0
HCLKRM
(internal/external)
(AHCLKRCTL.15)
HCLKRP
(polarity)
(AHCLKRCTL.14)
AHCLKR
pin
ACLKR
pin
1
0
1
0
0
1
(ACLKRCTL.5)
(internal/external)
CLKRM
CLKRP
(polarity)
(ACLKRCTL.7)
XCLK
(from Figure 15)
ASYNC
(ACLKXCTL.6)
RCLK
HCLKRDIV
(AHCLKRCTL[11−0])
Divider
/1... /32
CLKRDIV
(ACLKRCTL[4−0])
1094
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multichannel Audio Serial Port (McASP)
24.0.21.2 Receive Clock
The receiver has a clock generation circuit identical to (but independent of) that of the transmitter. The
receive bit clock, ACLKR, (
) may be either externally sourced from the ACLKR pin or
internally generated, as selected by the CLKRM bit. If internally generated (CLKRM = 1), the clock is
divided down by a programmable divider (CLKRDIV) from the receive high-frequency master clock
(AHCLKR). Regardless if ACLKR is either internally generated or externally sourced, polarity of the clock
may be programmed (CLKRP) to be either rising or falling edge.
The receive high-frequency master clock, AHCLKR, may be either externally sourced from the AHCLKR
pin or internally generated, as selected by the HCLKRM bit. If internally generated (HCLKRM = 1), the
clock is divided down by a programmable divider (HCLKRDIV) from AUXCLK. The receive high-frequency
master clock may be (but is not required to be) output on the AHCLKR pin where it is available to other
devices in the system. Regardless if AHCLKR is either internally generated or externally sourced, polarity
of the high-frequency clock may be programmed (HCLKRP) to be either rising or falling edge.
The receiver also has the option to operate synchronously from the ACLKX and AFSX signals. This is
achieved when the ASYNC bit in the transmit clock control register (ACLKXCTL) is cleared to 0. See
for details on McASP operation when ACLKXCTL.ASYNC = 0.
The receive clock configuration is controlled by the following registers:
•
ACLKRCTL
•
AHCLKRCTL
Figure 24-16. Receive Clock Generator Block Diagram