SH7144 Datasheet, PDF (128/773 Pages) Renesas Technology Corp – Hitachi SuperH RISC engine

6.8.1
Handling Interrupt Request Signals as Sources for DTC Activating and CPU
Interrupt, but Not DMAC Activating
1. Do not select DMAC activating sources or clear the DTE bit to 0.
2. For DTC, set the corresponding DTE bits and DISEL bits to 1.
3. Activating sources are applied to the DTC when interrupts occur.
4. When the DTC performs a data transfer, it clears the DTE bit to 0 and sends an interrupt
request to the CPU. The activating source is not cleared.
5. The CPU clears interrupt sources in the interrupt processing routine then confirms the transfer
counter value. When the transfer counter value is not 0, the CPU sets the DTE bit to 1 and
allows the next data transfer. If the transfer counter value = 0, the CPU performs the
necessary end processing in the interrupt processing routine.
6.8.2
Handling Interrupt Request Signals as Sources for Activating DMAC, but Not
CPU Interrupt and DTC Activating
1. Select DMAC activating sources and set the DME bit to 1. Then, CPU interrupt and DTC
activating sources are masked regardless of the settings of the interrupt priority register and the
DTC register.
2. Activating sources are applied to the DMAC when interrupts occur.
3. The DMAC clears the interrupt sources when starting transfer.
6.8.3
Handling Interrupt Request Signals as Source for DTC Activating, but Not CPU
Interrupt and DMAC Activating
1. Do not select DMAC activating sources or clear the DME bit to 0.
2. For DTC, set the corresponding DTE bits to 1 and clear the DISEL bits to 0.
3. Activating sources are applied to the DTC when interrupts occur.
4. When the DTC performs a data transfer, it clears the activating source. An interrupt request is
not sent to the CPU, because the DTE bit is hold to 1.
5. However, when the transfer counter value = 0 the DTE bit is cleared to 0 and an interrupt
request is sent to the CPU.
6. The CPU performs the necessary end processing in the interrupt processing routine.
Rev. 2.0, 09/02, page 88 of 732