DMA linked list on LCP1769

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by pauls on Thu Mar 15 09:15:52 MST 2012

[FONT=Arial]I have my SSP/DMA linked list transfer working on my LPC1769 demo board. Ready for when I get the real target on the LPLC1777, when the electical boys do thir stuff :rolleyes:.[/FONT]

[FONT=Arial]I have SSP0 master connected to SSP1 slave, so I can test the SSP/DMA links out and its working OK :).[/FONT]

[FONT=Arial]I want so send a status message back over the SSP from the slave to the master but when I try this :eek:[/FONT]

[FONT=Arial]I get blocked at the following line in the send :-[/FONT]

[B][COLOR=#7f0055][COLOR=#7f0055][FONT=Arial]while[/FONT][/COLOR][/COLOR][/B][FONT=Arial] ( (LPC_SSP1->[COLOR=#0000c0][COLOR=#0000c0]SR[/COLOR][/COLOR] & (SSPSR_BSY|SSPSR_RNE)) != SSPSR_RNE );[/FONT]

[FONT=Arial]I can get passed this blocking if I send just after the SSP's are initialised or after the first DMA transmit, but after or during the linked list items, I just get blocked with the Receive FIFO Not Empty.[/FONT]

[FONT=Arial]I have tryed to to free the recieve fifo with LPC_SSP1->[COLOR=#0000c0][COLOR=#0000c0]ICR[/COLOR][/COLOR] , but that did not work.[/FONT]

[FONT=Arial]Has any one seen this one before?[/FONT]

[FONT=Arial]I did find the first linked list item is actualy controls the second DMA transfer, the standard config contols the first one :confused:.[/FONT]


[FONT=Arial]Paul S[/FONT]