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That delay between bytes is based on how long it takes the chip to move the next byte from its internal buffer to the output shift registers.
In what size chunks? As written on the message, no matter how many bytes sent at once, the delay is same.
If the chip is clocked slowly, then this will show at the higher frequencies as a larger gap between bytes. I have no fydi how fast the USB transmit the data.
usb – FTHL FTDI consecutive SPI bytes delay problem – Electrical Engineering Stack Exchange
If you make a single call, add the appropriate chip select enable and disable flags see below. I tried to recreate the problem you describe, but I wasn’t able to exactly. Sign up using Facebook.
Latency timer really shouldn’t matter because that is simply a timeout before USB will send an incomplete packet. Also, delay between bytes should be a setting somewhere. LatencyTimer would help, but it shows no difference no matter the value used 10, delay remain 64uS between consecutive bytes.
FTDI FTH USB 12Mbps results – Black Mesa Labs
I’m still surprised some people can reach high transfer speeds out of the box and using the provided lib. I’ve used sample code provided with sample-dynamic. Here are some things to check. I check the SPI side because that’s the end of the line and I can easily check with logic analyzer. Here is some quick example code on how to send multiple data bytes in case it helps. I’ve contacted FTDI support, they asked me to update the libraries to latest one which I didthen they would not provide further support.
If this is a custom board design, or you bought a discount FTH adapter board, make sure it has the correct system clock frequency. GCC Library and code from: This is what it looked like on my logic analyzer when I output 6 bytes at once at a clock rate of 5MHz. Also, I use master spi mode, write-only, there shouldn’t be any handshaking involved. Email Required, but never shown. Back in the early days before people understood the issues, adding a USB serial converter to something that worked fine on a local bus serial port could completely break its usability.
There is is a small delay between bytes, but nowhere near as large as 64us. That’s often now understood, but SPI can involve coordination with other signals like selects, so it’s easy to imagine being hobbled by bus framing rt232hl unable to leverage the theoretical data rate that would apply to larger transfers. However, between each byte, there is a 64uS delay so it means that no matter how high is the SPI clock, the data transfer takes minutes instead of seconds.
USB peripherals can slow to a crawl if they only get a byte or few moved per ft232bl. Sign up using Email and Password. There must be something to fix because there are numerous examples of people reaching high transfer rates. How are you delivering the data to the drivers?