Writing on file slowly! about ch376msc HOT 3 OPEN

Hi, thanks.
What communication interface you use? If its serial then you can choose a higher baud rate(up to 115200), in case of using SPI the default speed is low (125kHz) in sake of stability if e.g. using long cables on a breadboard , but you can use these function-like macros when creating an object : (in case of Arduino with 16MHz Sys Clock, the maximum value can be 8MHz, but on this speed the communication it can become unreliable.Try with short wires)
SPI_SCK_KHZ( ) or SPI_SCK_MHZ( ) .
E.g.

Ch376msc flashDrive( 10, SPI_SCK_MHZ(2) ); // CS pin, com speed
// or
Ch376msc flashDrive( 10, 9, SPI_SCK_MHZ(2) );// CS pin, INT pin, com speed

In addition, the module also needs some time to save the data stored in the buffer to the USB drive. Have you tried with another flash-drive or to format the drive with external software . To be easy to implement for Arduino, the library use blocking functions (wait for answer from module)

from ch376msc.

Thanks for your reply. I have done all of them. I am using SPI communication with 12MHZ SCK and every 128 bytes is written at 4 milliseconds. Is it normal?

from ch376msc.

Yes, that is normal ,we have to wait with the next command until the CH376 finish with file writing otherwise data loss will occur. The chip will inform the MCU when is ready to receive the next command or data. The most time consuming part is when writing continuously and the CH376 internal buffer(512byte) is filled up, then the chip require longer time to do some internal processes, this is much depends on the usb-drive used. Here you can find more details about the drives i have been used.
2GB no name drive, worst case is more than 91 ms waiting for the module.

32GB PNY, worst case is 3.5 ms waiting for the module.

from ch376msc.