Hello,
I am using the USB VCOM app to transfer ADC data from the XMC4500 Relax kit to my PC (using Matlab).
I measured the transfer time for a buffer of 3 bytes and get a result of around 120µs (around 8kHz), which is quite slow comparing to its max speed of 12Mbps. I would like to ask if this speed is fixed or there is any way to increase it ?
I already tried the following methods:
- Change the clock speed in the DAVE App Configuration of CLK001: speed unchanged
- Change the baud rate on PC: speed unchanged
- Send 3 bytes separately using USBD_VCOM_SendByte: transfer time reduced to around 10µs but only 1 or 2 bytes arrived to PC. I don't understand why.
My goal is to reduce the transfer time for 3 bytes of data to < 20µs. Here is my main:
int main(void)
{
// status_t status; // Declaration of return variable for DAVE3 APIs (toggle comment if required)
int8_t byte_received = 0;
uint16_t Bytes = 0;
char TxBuffer[3];
uint16_t i,j;
DAVE_Init(); // Initialization of DAVE Apps
USBD_VCOM_Init();
TxBuffer[0] = '+';
TxBuffer[1] = 'A';
TxBuffer[2] = 'B';
while(1)
{
/* Main USB management task */
CDC_Device_USBTask(&USBD_VCOM_CDCInterface);
/* Check if data received */
Bytes = USBD_VCOM_BytesReceived();
if (Bytes)
{
USBD_VCOM_ReceiveByte(&byte_received);
for(i=0;i<1000;i++)
{
/* The IO004 app connected to a LED output to measure the transfer time */
IO004_SetOutputValue(IO004_Handle0,1);
USBD_VCOM_SendData(TxBuffer,3); // Pulse of 120µs shown on oscilloscope
IO004_SetOutputValue(IO004_Handle0,0);
for(j=0;j<1000;j++); // Delay to distinguish the transfer time on oscilloscope
}
}
}
return 0;
}
Thank you in advance.
