Information

When MSC[MCGEN] becomes disabled, the CMT module does not set MSC[EOCF] at
the end of the last modulation cycle.
If MSC[EOCIE] is high when MSC[EOCF] is set, the CMT module will generate an
interrupt request or a DMA transfer request.
MSC[EOCF] must be cleared to prevent from being generated by another event like
interrupt or DMA request, after exiting the service routine. See the following table.
Table 38-24. How to clear MSC[EOCF]
DMA[DM
A]
MSC[EOCIE] Description
0 X MSC[EOCF] is cleared by reading MSC followed by an access of CMD2 or CMD4.
1 X MSC[EOCF] is cleared by the CMT DMA transfer done.
The EOC interrupt is coincident with:
• Loading the down-counter with the contents of CMD1:CMD2
• Loading the space period register with the contents of CMD3:CMD4
The EOC interrupt provides a means for the user to reload new mark/space values into
the modulator data registers. Modulator data register updates will take effect at the end of
the current modulation cycle.
NOTE
The down-counter and space period register are updated at the
end of every modulation cycle, irrespective of interrupt
handling and the state of MSC[EOCF].
CMT interrupts and DMA
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
864 Freescale Semiconductor, Inc.