Honored Contributor II
03-13-2011 03:14 PM
Hi,I have the DE1 dev Board and using it with Quartus 2 10.1 SP1. So I want to access an SD-Card plugged into the DE1's sd slot without a NIOS architecture, just pure vhdl logic. That is no problem, as I am doing that in some state machine logic then, but it seems there is no input from the wires / connections when driving the card into the SPI mode. I read just 0 from SD_DAT0, regardless which command I send either (CMD0 in that case would init SPI mode as descripted on the papers.) I managed to add all the related pins for the sd-card from the "DE1_SD_Card_Audio" example and well checked it too with the board layout pdf file if it is correct. nCEO pin is set to regular I/O. The SD-Cards (no HC) are at different size, one is 64MB and the other 2GB. Here is an simplified version of the code I created in vhdl so far using some sd papers / tutorials. 1. After power on hold the card 1ms idle. 2. Then CS (DAT3) and DI (CMD) = 1, clock SD_CLK for 74 times. 3. CS (DAT3) = 0 & Sending CMD0 in serial bit stream aligned to the clock. 4. DI (CMD) = 1 & Wait 8 bytes long (so far I tried from 0-10) 8 * 8 cycles for the response while clock SD_CLK. 5. Read the possible response from negated SD_DAT0. But response is always 0. Is there any known issue for the DE1 SD-Card slot or pins/wires assignment notices to consider? I debugged and simulated already, the pins are successfully connected to the outlets by the assembler. I someone wants to investigate my vhdl code files, I will post him/her via p.m. Thank you.