Copying large files to USB datalogger using SPI: How to decrease USB write time?
BonanzaMan
Posts: 17
I am creating a portable device that (along with other functions) copies image (.JPG) files from an SD card to a USB stick. I am using Kye's SD-MMC_FATEngine object for reading the SD cards. For the USB writing, I am using the USB data logger (#27937) and the DataloggerSPI object. Each file I want to copy is ~650k. In my preliminary testing, I do an iterative 20k read(SD) and write(USB) loop that ulitimately works but the 20k USB write (using writeToFile) takes about 20 seconds to complete. I suspect that the USB write is chugging along at 9600 bps. Looking at the object and the demo program, its not clear to me how to jack up the baud rate of the USB stick in SPI mode.... I have notived a couple references to changing baud rate in UART mode, but none in SPI. So two questions:
1. How does one change the baud rate of the USB logger in SPI mode? I've tried the method in the Vinculum app note and it doesn't seem to work.
2. What would be faster, using the USB logger in UART mode or SPI mode?
Thanks!
Greg
1. How does one change the baud rate of the USB logger in SPI mode? I've tried the method in the Vinculum app note and it doesn't seem to work.
2. What would be faster, using the USB logger in UART mode or SPI mode?
Thanks!
Greg