Send 16bits buffer via USB Virtual COM Port.

Question

Hi, I have a buffer with 65000 values in 16 bits from the ADC read that I need to provide to my computer running a python code.Any suggestion how can I handle this in both sides?I'm trying to use this function but I'm getting weird data when I'm listening the COM port with Putty. // Generalized function to transmit any 16bits buffer over USB
void send_16b_buffer_over_usb(uint16_t *buffer, uint32_t buffer_size)
{
 uint32_t total_bytes = buffer_size * BYTES_PER_SAMPLE; // Total size of the buffer in bytes
 uint32_t bytes_sent = 0;
 uint8_t result = USBD_OK;

// Send the buffer in chunks
 while (bytes_sent < total_bytes)
 {
 // Calculate the remaining bytes to be sent
 uint32_t bytes_to_send = (total_bytes - bytes_sent > CHUNK_SIZE) ? CHUNK_SIZE : (total_bytes - bytes_sent);

// Send the current chunk of data
 result = CDC_Transmit_HS((uint8_t*)&buffer[bytes_sent / BYTES_PER_SAMPLE], bytes_to_send);

// Wait for the USB transmission to complete
 while (result == USBD_BUSY)
 {
 result = CDC_Transmit_HS((uint8_t*)&buffer[bytes_sent / BYTES_PER_SAMPLE], bytes_to_send);
 }

// If the transmission was successful, update the sent bytes counter
 if (result == USBD_OK)
 {
 bytes_sent += bytes_to_send;
 }
 else
 {
 // Handle transmission failure (optional)
 break;
 }
 }
} If I do something simple like this it work fine: /* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
uint8_t *data = "Hello World from USB CDC
";
/* USER CODE END 0 */

int main(void)
{
 HAL_Init();
 
 SystemClock_Config();

MX_GPIO_Init();
 MX_USB_DEVICE_Init();

while (1)
 {
	 CDC_Transmit_FS(data, strlen(data));
	 HAL_Delay (1000);
 }
} Thank you.

fposser · Accepted Answer

With this code I was able to read the correct values.Thank you for the support.   def read_serial_data(buffer_size, output_file): # Buffer to store the received binary data buffer = bytearray() while len(buffer) < buffer_size: # Read binary data from UART data = ser.read(buffer_size - len(buffer)) # Read only the remaining bytes needed to fill the buffer if data: buffer.extend(data) # Append received data to the buffer print(f"Received {len(data)} bytes, total: {len(buffer)} bytes") if len(buffer) >= buffer_size: print("Buffer filled.") break # Convert the buffer to a hexadecimal string hex_data = buffer.hex() # Insert commas between every four hexadecimal characters formatted_hex_data = ','.join(hex_data[i:i + 4] for i in range(0, len(hex_data), 4)) # Save the formatted hexadecimal string to a text file with open(output_file + "_hex.txt", "w") as f: f.write(formatted_hex_data) print(f"Saved {len(formatted_hex_data)} characters to '{output_file}_hex.txt'") # Convert groups of four hex values to 16-bit numbers and then to decimal decimal_values = [] for i in range(0, len(hex_data), 4): # Process 8 hex characters (4 bytes) at a time if i + 4 <= len(hex_data): low_part = hex_data[i:i + 2] high_part = hex_data[i + 2:i + 4] combined_value = int(high_part + low_part, 16) decimal_values.append(combined_value) # Save the decimal values to a new file with open(output_file + "_decimal.txt", "w") as f: for value in decimal_values: f.write(f"{value}
") print(f"Saved {len(decimal_values)} decimal values to '{output_file}_decimal.txt'")

Andrew Neil · Answer

@fposser wrote:I'm trying to use this function but I'm getting weird data when I'm listening the COM port with Putty.Define "weird".You're sending raw binary data - so that would not be expected to appear as readable text on a terminal!

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