Rich Simmons
Member
Thanks, mbolivar and crenn, for the information. I think that you're right, the LTC1659 acquires B11 of the data on the rising edge of the first clock following /CS low. There is a minimum time (no max) specified for /CS [NSS]to return high following the 12th clock rising edge, and a minimum time (no max) for /CS to remain high before the next cycle. So as you say, crenn, we should be able to make this work. I'll let you know!
Thanks,
Rich Simmons
gbulmer
Moderator
micah - I have some of those microphones too (somewhere). I got them to do time-shifted bat recording/replay.
I'd be interested in how well they work.
Remember, if you want to capture a 50KHz signal, you must sample, at least, at twice that frequency (Shannon-Nyquest sampling theorem) and ensure their are no signal components about 50Khz.
Designers recommend sampling at many times higher than 2x, because it is easier to make a filter, and 'decimating' (throwing some away) the samples.
Has anyone got working example code for the maple-SDfat-DMA library?
I'm a noob trying to figure this out and I can't get anything working - just compile errors all over the place (which seem related to the Arduino port).
I can get Pol Pla's DMA exmple from http://polplaiconesa.com/tutorials/SPI+DMA.html working OK, but how do I get that working with and SD card?
Thanks in advance.
-steve
micah
Member
nevets, did you see manitou's post from the last page? he posted his version of Sd2Card.cpp which included an updated write function along with some benchmarks.
micah
Member
So I'm finally sitting down to work on my project and am having some trouble getting Manitou's changed Sd2Card.cpp working with the FileSys.pde example. The Sd2Card::Init() function no longer takes any input, so I got rid of that, but now it seems to be getting hung up in the SdVolume::init function after cacheFlush() is finished. The function that gets hung up seems to be Sd2Card::readData
My goal was to use the existing examples with Manitou's changes, since the SdFile write functions at first appeared to be compatible with them. But now I'm not so sure! Is much more work needed to get SdFile working with the changes?
P.s. I should mention that my internet access is up and down so I'm referencing these functions and classes from memory. My bad if I messed up any of the names!
micah
Member
Alright, I've made some progress. I got polpla's MapleSdFat repository working with manitou's Sd2Card.cpp file and committed to a fork here.
But now I'm having some issues!!! I have one sketch for which Sd2Card.init() is successful, and another for which it fails (the one I'm currently working on). I cannot understand how they are different in any way that would make this happen!
So without further ado, here are the two files, appropriately named "success.cpp" and "failure.cpp". Any ideas? The
micah
Member
Here are the errors for the failing one:
Error: CMD0
Error: Sd2Card::init()
card.init failed
254 != 0
Error: Read
Error: Sd2Card::waitStartBlock()
Error: Sd2Card::readData()
Error: SdVolume::init() Cache for read
254 != 0
Error: Read
Error: Sd2Card::waitStartBlock()
Error: Sd2Card::readData()
Error: SdVolume::init() Cache for read2
volume.init failed
openRoot failed
254 != 0
Error: Read
Error: Sd2Card::waitStartBlock()
Error: Sd2Card::readData()
Could not open file!
polpla
Member
timbresmith added manitou's suggestion to the library. It is already updated in Github: https://github.com/polpla/Maple-SDFat-DMA
Hope it is helpful to all!
pmp0x
Member
Hey!
I'm working on the WiFly and needed to use the SPI-Interface… Because I had some unexpected behavior I looked into the SPI-Interface code and come upon two things I would like to discuss…
first the one in HardwareSpi.cpp
<br />
void HardwareSPI::write(const uint8 *data, uint32 length) {<br />
uint32 txed = 0;<br />
while (txed < length) {<br />
txed += spi_tx(this->spi_d, data + txed, length - txed);<br />
}<br />
}<br />Firs use the supplied function from spi.c this should avoid some overhead actually.
But the more important one. For me it seemed quiet crucial to read from the transmit register once after transmitting all data Because even though the other side doesn't send data there seems to be data in the TX-buffer
void HardwareSPI::write(const void *data, uint32 length) {
// use the offered function from spi.c
spi_tx(this->spi_d, data, length);
spi_rx_reg(this->spi_d);
}the other is the spi.c directly <i>libmaple's spi.c</i>
uint32 spi_tx(spi_dev *dev, const void *buf, uint32 len) {
uint32 txed = 0;
uint8 byte_frame = spi_dff(dev) == SPI_DFF_8_BIT;
while (spi_is_tx_empty(dev) && (txed < len)) {
if (byte_frame) {
dev->regs->DR = ((const uint8*)buf)[txed++];
} else {
dev->regs->DR = ((const uint16*)buf)[txed++];
}
}
return txed;
}<i>changed spi.c</i>
uint32 spi_tx(spi_dev *dev, const void *buf, uint32 len) {
uint32 txed = 0;
uint8 byte_frame = spi_dff(dev) == SPI_DFF_8_BIT;
while ((txed < len)) {
while(!spi_is_tx_empty(dev))
;
if (byte_frame) {
//spi_tx_reg((((const uint8*)buf)[txed++] & 0X0000) );
dev->regs->DR = ((const uint8*)buf)[txed++];
} else {
//spi_tx_reg(((const uint16*)buf)[txed++]);
dev->regs->DR = ((const uint16*)buf)[txed++];
}
}
return txed;
}I think the original code will just work with transfering one byte. Because after the first round through the while loop (equal to the first byte send over spi). The function spi_is_tx_empty() might return true (and therefor the 2nd byte can be put into the buffer) but thats not certain. But it becomes obvious if we want to transmit the 3rd byte. because now we have to WAIT till the TXE-flag turns and this will never be captured be the libmaple while loop.
Therefore I thing it needs to be this "blocking" transfer if we want to transmit more than one byte. (see fig. 239 in the documentation)
BUT because I'm not 100% certain I would like to discuss my changes ;)
dinau
Member
Hi,
I've improved SdFatMaple-vld library.
I will update download file(v03) later.
https://bitbucket.org/dinau/sdfatmaple-vld/wiki/Home
By optimizing SPI read/write routin (without DMA),
SD card read/write speed is up by multiple from 1.5 to 2.5.
2G byte MicroSD card [Transcend], FAT16
( Using SdFatBench.pde and Olimexino-STM32(compatible Maple rev5 ) )
Before: v02
SD card read/write speed,
[SPI clock], write, read
[4.5MHz], 109kb/sec, 168kb/sec
[ 9MHz ], 120kb/sec, 192kb/sec
[18MHz ], 119kb/sec, 192kb/sec
After: v03
Improved SD card read/write speed,
[SPI clock], write, read
[4.5MHz], 153kb/sec, 289kb/sec
[ 9MHz ], 176kb/sec, 396kb/sec
[18MHz ], 192kb/sec, 485kb/sec
([kb/sec]=[kilo byte/sec])
I found the latest version of Maple-SDFat-DMA yesterday,
https://github.com/polpla/Maple-SDFat-DMA
I'd like to try the DMA version, someday.
Regards
dinau
gbulmer
Moderator
dinau - That looks impressive.
However, I am a bit confused.
On your post you wrote, for example:
"[18MHz ], 192kb/sec, 485kb/sec",
"kb" means kilobits, so read speed is 485000 bits/second
At https://bitbucket.org/dinau/sdfatmaple-vld/wiki/Home it says
"18.0MHz 192[KB/sec] 485[KB/sec]"
"KB" in SI units is Kelvin Bytes, so I assume that should be "kB" for kilobytes, which is 485000 Bytes/second, or 3880000 bits/second
Which is it?
(Edited to make "kb" vs "KB" it clearer)
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