Libraries
Background
tollosVCom.c – USB Virtual COM port functions
The vcom functions provide character I/O over a USB Virtual COM port.It is assumed that there is a primary, or only one, USB link so these functions do not specify a device number.
| Functions | |
|---|---|
| vcomGetc | get character from vcom device |
| vcomInit | initialize serial vcom device |
| vcomPutc | send character to vcom device |
| vcomStop | stop the vcom device |
vcomGetc – get character from vcom device
int vcomGetc(void);
returns character read from vcom, or −1 if none there or vcom has not been initialized
This function does not block. It returns an int so that errors are distinct, and will also allow extension.
vcomInit – initialize serial vcom device
int vcomInit(void);
returns 0 if OK, negative if interrupt already in use
This does not switch a software connection as this is device-dependent (port, pin, and direction), so the caller should use bitSet to make the connection before calling this.
vcomPutc – send character to vcom device
int vcomPutc(int ch);
ch – character to send
returns 0 if OK, or −1 if vcom has not been initialized, or
−2 if there is a data overrun (bytes have been queued faster
than they could be sent to the host)
This function does not block.
Note that this must not be called from an interrupt handler that has a higher priority than USB.
vcomStop – stop the vcom device
void vcomStop(void);
This does not switch a software connection because this is device-dependent (port, pin, and direction), so the caller should use bitSet to make the connection an input after calling this.
vcomStop has no effect if vcom has not been initialized.