topic LPC1758 Interrupt IN endpoint does not retire blank DMA descriptors in LPC Microcontrollers https://community.nxp.com/t5/LPC-Microcontrollers/LPC1758-Interrupt-IN-endpoint-does-not-retire-blank-DMA/m-p/523577#M6213 <HTML><HEAD></HEAD><BODY><STRONG>Content originally posted in LPCWare by ejg on Wed Jan 27 03:58:25 MST 2016</STRONG><BR /><SPAN>Hi,</SPAN><BR /><BR /><SPAN>I'm running my LPC1758 as a USB device and sending data to the host over a bulk IN endpoint and an interrupt IN endpoint. In both cases the length of the data I'm sending is equal to the maximum packet size of the endpoint.</SPAN><BR /><BR /><SPAN>The user manual states that:</SPAN><BR /><HR /><SPAN style="color: #0000ff;"><STRONG>Quote: </STRONG><BR />If the last buffer length completes on a MaxPacketSize packet boundary, the device software must program the next DD with DMA_buffer_length field 0, so that an empty packet is sent by the device to mark the end of the USB transfer for the host.</SPAN><HR /><BR /><BR /><SPAN>The weird thing is on the bulk endpoint these empty DMA descriptors will have their status set to retired, the interrupt endpoint doesn't retire them.</SPAN><BR /><BR /><SPAN>I've managed to fudge the code together to get everything working, just wondered if anyone understood why this is happening?</SPAN></BODY></HTML> Wed, 15 Jun 2016 16:45:05 GMT lpcware 2016-06-15T16:45:05Z LPC1758 Interrupt IN endpoint does not retire blank DMA descriptors https://community.nxp.com/t5/LPC-Microcontrollers/LPC1758-Interrupt-IN-endpoint-does-not-retire-blank-DMA/m-p/523577#M6213 <HTML><HEAD></HEAD><BODY><STRONG>Content originally posted in LPCWare by ejg on Wed Jan 27 03:58:25 MST 2016</STRONG><BR /><SPAN>Hi,</SPAN><BR /><BR /><SPAN>I'm running my LPC1758 as a USB device and sending data to the host over a bulk IN endpoint and an interrupt IN endpoint. In both cases the length of the data I'm sending is equal to the maximum packet size of the endpoint.</SPAN><BR /><BR /><SPAN>The user manual states that:</SPAN><BR /><HR /><SPAN style="color: #0000ff;"><STRONG>Quote: </STRONG><BR />If the last buffer length completes on a MaxPacketSize packet boundary, the device software must program the next DD with DMA_buffer_length field 0, so that an empty packet is sent by the device to mark the end of the USB transfer for the host.</SPAN><HR /><BR /><BR /><SPAN>The weird thing is on the bulk endpoint these empty DMA descriptors will have their status set to retired, the interrupt endpoint doesn't retire them.</SPAN><BR /><BR /><SPAN>I've managed to fudge the code together to get everything working, just wondered if anyone understood why this is happening?</SPAN></BODY></HTML> Wed, 15 Jun 2016 16:45:05 GMT https://community.nxp.com/t5/LPC-Microcontrollers/LPC1758-Interrupt-IN-endpoint-does-not-retire-blank-DMA/m-p/523577#M6213 lpcware 2016-06-15T16:45:05Z