From c56a18fb38e4d9d11b6799eef395a6dc667750e7 Mon Sep 17 00:00:00 2001 From: patacongo Date: Tue, 21 Feb 2012 19:16:41 +0000 Subject: Fix SDIO DMA (finally) git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4409 42af7a65-404d-4744-a932-0658087f49c3 --- nuttx/configs/stm3240g-eval/README.txt | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'nuttx/configs/stm3240g-eval/README.txt') diff --git a/nuttx/configs/stm3240g-eval/README.txt b/nuttx/configs/stm3240g-eval/README.txt index ef26c0088..e4902947e 100755 --- a/nuttx/configs/stm3240g-eval/README.txt +++ b/nuttx/configs/stm3240g-eval/README.txt @@ -720,9 +720,23 @@ Where is one of the following: configuration. 2. RS-232 is disabled, but Telnet is still available for use as a console. + Since RS-232 and SDIO use the same pins (one controlled by JP22), RS232 + and SDIO cannot be used concurrently. 3. This configuration requires that jumper JP22 be set to enable SDIO operation. + 4. In order to use SDIO without overruns, DMA must be used. The STM32 F4 + has 192Kb of SRAM in two banks: 112Kb of "system" SRAM located at + 0x2000:0000 and 64Kb of "TCM" SRAM located at 0x1000:0000. It appears + that you cannot perform DMA from TCM SRAM. The work around that I have now + is simply to omit the 64Kb of TCM SRAM from the heap so that all memory is + allocated from System SRAM. This is done by setting: + + CONFIG_MM_REGIONS=1 + + Then DMA works fine. The downside is, of course, is that we lose 64Kb + of precious SRAM. + ostest: ------ This configuration directory, performs a simple OS test using -- cgit v1.2.3