Hi tclong, The DTC or DMA can be used when the MMF is active with no problems if your are transferring between I/O to RAM or RAM to RAM. The issue is that the CPU access to flash memory is translated by the MMF and other bus masters are not. So if you had a const area defined in your flash image, you could access it symbolically and it will work for cpu access. If you load that const address into a DMA/DTC as the source, it would use the untranslated address, not the re-mapped address. For the hal drivers - the callback function at the hal level is equivalent to the H8s interrupt handles. The difference is that the event passed into the callback is used instead of checking the device interrupt registers. The SSP will use the DTC for some frameworks - if you look at the module stacks in the configurator you will see them. In some cases, they are optional and can be disabled. In general, you should not have an issue unless you are using Guix & the GLCD (which is a bus master) or the Audio Playback framework (which uses the DTC). Both of these cases can still be done if the const data is stored in QSPI flash which is not mapped via the MMF. -Gary
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