LeafLabs Garden » Topic: How could I know whether my SPI buffer is overflow or not?

LeafLabs Garden » Topic: How could I know whether my SPI buffer is overflow or not? http://forums.leaflabs.com/topic.php?id=1066 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:24:13 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://forums.leaflabs.com/search.php gulu2065 on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6603 Mon, 26 Sep 2011 01:21:08 +0000 gulu2065 6603@http://forums.leaflabs.com/ gbulmer, I have figure it out. Thanks for your kind help! gulu2065 on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6600 Sun, 25 Sep 2011 17:30:16 +0000 gulu2065 6600@http://forums.leaflabs.com/ gbulmer, Thank, that code works! Now there is no doubt that it is overflow. I am trying to use DMA so solve this problem. But I can't figure out how to do it. Can you have a look at this ? thanks <a href="http://forums.leaflabs.com/topic.php?id=1072" rel="nofollow">http://forums.leaflabs.com/topic.php?id=1072</a> gbulmer on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6599 Sun, 25 Sep 2011 17:08:06 +0000 gbulmer 6599@http://forums.leaflabs.com/ gulu2065 - what is the error message? It might be something earlier in the file. do you get the same error if you change it to: <pre><code>bool hasOverrunOccurred() { // return SPI1_BASE->SR & SPI_SR_OVR; return 0xFFFFFFFF; }</code></pre> gulu2065 on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6575 Sun, 25 Sep 2011 00:22:36 +0000 gulu2065 6575@http://forums.leaflabs.com/ Hi glulmer, Besides, when I compile this sentence, it shows error. do you know what the problem is? bool hasOverrunOccurred() { return SPI1_BASE->SR & SPI_SR_OVR; } Thanks, gulu2065 on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6574 Sat, 24 Sep 2011 22:00:28 +0000 gulu2065 6574@http://forums.leaflabs.com/ Hi glulmer, It seems the RAM is not that big. When I compile this, it show this error. I guess the buffer is too big, right? elf section <code>.bss' will not fit in region</code>ram' c:/users/guo/desktop/maple/hardware/tools/arm/bin/../lib/gcc/arm-none-eabi/4.4.1/../../../../arm-none-eabi/bin/ld.exe: region `ram' overflowed by 1096 bytes Can I store the data in the flash, I see it is much bgiger than the RAM. gbulmer on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6566 Sat, 24 Sep 2011 17:52:25 +0000 gbulmer 6566@http://forums.leaflabs.com/ gulu2065 - I had understood that your use case would allow the program to capture the data, store it, then upload it. Is that not the case? If you can store it, try something like: <pre><code>byte buff[16422]; int i=0; void loop() { buff[i++] = spi.read(); if (i>= sizeof(buff)) { // Print out the response received. for (int j=0; j<i; j++) { SerialUSB.println(response, BIN); } i=0; } }</code></pre> (usual WARNINGS: I have not compiled or tested this code) mbolivar on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6557 Sat, 24 Sep 2011 14:30:46 +0000 mbolivar 6557@http://forums.leaflabs.com/ No, unfortunately, the USB serial port is not very fast. The USB peripheral is quite fast, but we don't have the necessary library support for fast transfers over USB yet. And I'm sorry, but I don't know enough about your application to know when you have to tear down your SPI port. Is it very important never to miss a byte? If so, I guess you'd need to stop as soon as the first overrun condition happens. If it's not that important, then maybe you can recover from the error somehow. gulu2065 on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6556 Sat, 24 Sep 2011 14:25:20 +0000 gulu2065 6556@http://forums.leaflabs.com/ I guess the USB serial is not fast enough as to reach 1.6Mhz. How could I know when should I end the SPI in case of overflow? mbolivar on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6555 Sat, 24 Sep 2011 14:24:40 +0000 mbolivar 6555@http://forums.leaflabs.com/ If you have an unread byte, and the SPI master sends another one, then you get an "overrun condition". The second byte sent is lost. You can check if this has happened by checking the OVR flag in the status register (SR) for the SPI peripheral you're interested in, using this function: <pre><code>bool hasOverrunOccurred() { return SPI1_BASE->SR & SPI_SR_OVR; }</code></pre> <code>hasOverrunOccurred()</code> will return <code>true</code> if you've missed a byte, and <code>false</code> otherwise. If that happens, you need to clear the OVR flag in the status register. If you don't, then you won't be able to detect later overruns anymore -- <code>hasOverrunOccurred()</code> will just return <code>true</code> forever. You clear the OVR flag by reading the first unread byte, then reading the status register again. Here's some (untested) code that should do the trick: <pre><code>// Read the unread byte byte unread = spi.read(); // Read the status register uint32 sr = SPI1_BASE->SR;</code></pre> gulu2065 on "How could I know whether my SPI buffer is overflow or not?" http://forums.leaflabs.com/topic.php?id=1066#post-6554 Sat, 24 Sep 2011 14:11:02 +0000 gulu2065 6554@http://forums.leaflabs.com/ I use the SPI work on slave and read data from another chip. Here is my code. HardwareSPI spi(1); ... void setup() { .... spi.beginSlave(MSBFIRST, 0); } void loop() { byte response = spi.read(); // Print out the response received. SerialUSB.println(response, BIN); } It read data at the speed of 1.6Mhz. Thanks