Interconnectivity Page 2 of 5 Application Notes: Using PDIUSBD12 in DMA Mode Introduction to Protocol Based DMA Operation PDIUSBD12 has 6 endpoints, 2 control endpoints, 2 Generic endpoints and 2 Main endpoints The Main endpoints support DMA transfer In the protocol based DMA operation, the host application first ask the device's firmware to setup DMa transfer using vendor request which is sent through control endpoint, then it performs actual data transfer on the Main endpoints. After the setup of DMa controller, the host can transfer up to 64K bytes of data to the device without any firmware intervention A complete DMA transfer requires following two steps 1)Send a Setup DMA Request through control pipe, let the device to program the DMAC with DMA transfer direction start address and size of transfer eceived data packets on Main endp 2. Device's dMa states The Setup DMA Request is sent from the host as vendor request using control pipe. The devices response and action taken depend on its internal states of DMa IOCTL: Setup DMA/ NAK Overwrite previous setup DMA request IOCTL: Setup DMA/ ACK RUNNING Above DMA state diagram shows 3 DMA states in the device: IDLE, RUNNING and PENDING When there is no running or pending DMA operation, the device is in IDLE and the Setup DMA Request will be responded with ACK. If the device is in the process of a ransfer it is in the device to enter PENDING, which indicates there is a pending Setup dma Request. i the u RUNNING. Setup DMA Request received at RUNNING will be responded with NAK and caus device receives another Setup DMA Request in PENDING, the new request will overwrite the old Philips Semiconductors-Asia Product Innovation Centre Visithttp://www.flexi usD. conInterconnectivity Page 2 of 5 Application Notes: Using PDIUSBD12 in DMA Mode ______________________________________________________________________________________________ Philips Semiconductors - Asia Product Innovation Centre Visit http://www.flexiusb.com 1. Introduction to Protocol Based DMA Operation PDIUSBD12 has 6 endpoints, 2 control endpoints, 2 Generic endpoints and 2 Main endpoints. The Main endpoints support DMA transfer. In the protocol based DMA operation, the host application first ask the device’s firmware to setup DMA transfer using vendor request which is sent through control endpoint, then it performs actual bulk data transfer on the Main endpoints. After the setup of DMA controller, the host can transfer up to 64K bytes of data to the device without any firmware intervention. A complete DMA transfer requires following two steps: 1) Send a Setup DMA Request through control pipe, let the device to program the DMAC with DMA transfer direction, start address and size of transfer; 2) Send or received data packets on Main endpoint. 2. Device’s DMA States The Setup DMA Request is sent from the host as vendor request using control pipe. The device’s response and action taken depend on its internal states of DMA operation. Above DMA state diagram shows 3 DMA states in the device: IDLE, RUNNING and PENDING. When there is no running or pending DMA operation, the device is in IDLE and the Setup DMA Request will be responded with ACK. If the device is in the process of a DMA transfer, it is in RUNNING. Setup DMA Request received at RUNNING will be responded with NAK and causes the device to enter PENDING, which indicates there is a pending Setup DMA Request. If the device receives another Setup DMA Request in PENDING, the new request will overwrite the old one. IDLE PENDING RUNNING IOCTL: Setup DMA / ACK EOT IOCTL: Setup DMA / NAK EOT / ACK IOCTL: Setup DMA / NAK Overwrite previous setup DMA request