Enhanced Direct Memory Access (eDMA)MPC5606S Microcontroller Reference Manual, Rev. 7516 Freescale SemiconductorTCD.daddr = 0x2000TCD.doff = 4TCD.dsize = 2TCD.dlast_sga= -16TCD.int_maj = 1TCD.start = 1 (TCD.word7 should be written last after all other fields have been initialized)All other TCD fields = 0This generates the following sequence of events:1. IPS write to the TCD.start bit requests channel service2. The channel is selected by arbitration for servicing3. DMA engine writes: TCD.done = 0, TCD.start = 0, TCD.active = 14. DMA engine reads: channel TCD data from local memory to internal register file5. The source to destination transfers are executed as follows:a. read_byte(0x1000), read_byte(0x1001), read_byte(0x1002), read_byte(0x1003)b. write_word(0x2000) first iteration of the minor loopc. read_byte(0x1004), read_byte(0x1005), read_byte(0x1006), read_byte(0x1007)d. write_word(0x2004) second iteration of the minor loope. read_byte(0x1008), read_byte(0x1009), read_byte(0x100a), read_byte(0x100b)f. write_word(0x2008) third iteration of the minor loopg. read_byte(0x100c), read_byte(0x100d), read_byte(0x100e), read_byte(0x100f)h. write_word(0x200c) last iteration of the minor loop major loop complete6. DMA engine writes: TCD.saddr = 0x1000, TCD.daddr = 0x2000, TCD.citer = 1 (TCD.biter)7. DMA engine writes: TCD.active = 0, TCD.done = 1, DMAINT[n] = 18. The channel retiresThe DMA goes idle or services next channel.15.5.4.2 Multiple requestsThe next example is the same as the previous example, with the exception of transferring 32 bytes via twohardware requests. The only fields that change are the major loop iteration count and the final addressoffsets. The DMA is programmed for two iterations of the major loop transferring 16 bytes per iteration.After the channel’s hardware requests is enabled in the DMAERQ register, channel service requests areinitiated by the slave device.TCD.citer = TCD.biter .
