SPRUJF2A March 2026 – March 2026 AM13E23019
The DMA_TRIG_TX and DMA_TRIG_RX group registers are used to setup trigger signaling for the DMA. These registers (IMASK, RIS, MIS, ISET, ICLR) are present for any UCx configured as an I2C Commander or an I2C Target and can be found in the corresponding UNICOMMI2CC_REGS and UNICOMMI2CT_REGS register structures. See Section 9.2.3 for how the DMA trigger Event works and can be configured. Each DMA channel can be triggered by any of the conditions listed in the Section 9.2.3.1 and can send a DMA_DONE signal to the corresponding UCx module.
| Trigger Name | Register Structure | Register Group | Description |
|---|---|---|---|
| RXTRG | UNICOMMI2CC_REGS | DMA_TRIG_RX |
Controller receive FIFO event. Trigger when I2CC-configured UCx module's Receive FIFO contains >= IFLS.RXIFSEL defined bytes |
| TXTRG | UNICOMMI2CC_REGS | DMA_TRIG_TX |
Controller transmit FIFO event. Trigger when I2CC-configured UCx module's Transmit FIFO contains <= IFLS.TXIFSEL defined bytes |
| RXTRG | UNICOMMI2CT_REGS | DMA_TRIG_RX |
Target receive FIFO event. Trigger when I2CT-configured UCx module's Receive FIFO contains >= IFLS.RXIFSEL defined bytes |
| TXTRG | UNICOMMI2CT_REGS | DMA_TRIG_TX |
Target transmit FIFO event. Trigger when I2CT-configured UCx module's Transmit FIFO contains <= IFLS.TXIFSEL defined bytes |
Take an example where UC0 is configured with the I2CC IPMODE and UC1 is configured with the I2CT IPMODE. To use different DMA channels for each of the operations (controller-transmitter, controller-receiver, target-transmitter, target-receiver) four channels are set up as shown in Figure 24-20. For both UC modules, RXTRG is set as the trigger source for DMA_TRIG_RX and TXTRG is set as the trigger source for DMA_TRIG_TX. The DMA_DONE signal.