Add option for custom USB configuration / Fix receiving short string data from X-Plane

[jbliesener]

Setting -DUSB_CUSTOM and -I./include allows to specify a custom USB configuration from sketch file include/usb_custom.h

I use this together with platformio to handle a use case where I need a very specific USB configuration "FlightSim + dual Serial". It wouldn't make any sense to include this in the standard USB configurations, yet it is a valid use case. Therefore, I suggest to allow custom USB configurations. In my specific use case, my usb_custom.h file looks like this:

#if defined(__IMXRT1062__)
// Teensy 4.x

#define VENDOR_ID		0x16C0
#define PRODUCT_ID		0x0488
#define BCD_DEVICE		0x0212
#define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
#define MANUFACTURER_NAME_LEN	11
#define PRODUCT_NAME		{'T','e','e','n','s','y',' ','F','l','i','g','h','t',' ','S','i','m',' ','C','o','n','t','r','o','l','s'}
#define PRODUCT_NAME_LEN	26
#define EP0_SIZE              64
#define NUM_ENDPOINTS         6
#define NUM_INTERFACE         5
#define CDC_IAD_DESCRIPTOR    1       // Serial
#define CDC_STATUS_INTERFACE  0
#define CDC_DATA_INTERFACE    1
#define CDC_ACM_ENDPOINT      2
#define CDC_RX_ENDPOINT       3
#define CDC_TX_ENDPOINT       3
#define CDC_ACM_SIZE          16
#define CDC_RX_SIZE_480       512
#define CDC_TX_SIZE_480       512
#define CDC_RX_SIZE_12        64
#define CDC_TX_SIZE_12        64
#define CDC2_STATUS_INTERFACE 2       // SerialUSB1
#define CDC2_DATA_INTERFACE   3
#define CDC2_ACM_ENDPOINT     4
#define CDC2_RX_ENDPOINT      5
#define CDC2_TX_ENDPOINT      5
#define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
#define ENDPOINT3_CONFIG	ENDPOINT_RECEIVE_BULK + ENDPOINT_TRANSMIT_BULK
#define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
#define ENDPOINT5_CONFIG	ENDPOINT_RECEIVE_BULK + ENDPOINT_TRANSMIT_BULK
#define FLIGHTSIM_INTERFACE	4	// Flight Sim Control
#define FLIGHTSIM_TX_ENDPOINT	6
#define FLIGHTSIM_TX_SIZE	64
#define FLIGHTSIM_TX_INTERVAL	1
#define FLIGHTSIM_RX_ENDPOINT	6
#define FLIGHTSIM_RX_SIZE	64
#define FLIGHTSIM_RX_INTERVAL	1
#define ENDPOINT6_CONFIG	ENDPOINT_RECEIVE_BULK + ENDPOINT_TRANSMIT_BULK

#elif defined(__MK66FX1M0__) || defined(__MK64FX512__) || defined(__MK20DX256__) || defined(__MK20DX128__) || defined(__MKL26Z64__)
// Teensy 3.x

#define VENDOR_ID		0x16C0
#define PRODUCT_ID		0x0488
#define BCD_DEVICE		0x0211
#define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
#define MANUFACTURER_NAME_LEN	11
#define PRODUCT_NAME		{'T','e','e','n','s','y',' ','F','l','i','g','h','t',' ','S','i','m',' ','C','o','n','t','r','o','l','s'}
#define PRODUCT_NAME_LEN	26
#define EP0_SIZE		64
#define NUM_ENDPOINTS         9
#define NUM_USB_BUFFERS	20
#define NUM_INTERFACE		5
#define CDC_IAD_DESCRIPTOR	1	// Serial
#define CDC_STATUS_INTERFACE	0
#define CDC_DATA_INTERFACE	1
#define CDC_ACM_ENDPOINT	2
#define CDC_RX_ENDPOINT	3
#define CDC_TX_ENDPOINT	4
#define CDC_ACM_SIZE		16
#define CDC_RX_SIZE		64
#define CDC_TX_SIZE		64
#define CDC2_STATUS_INTERFACE	2	// SerialUSB1
#define CDC2_DATA_INTERFACE	3
#define CDC2_ACM_ENDPOINT	5
#define CDC2_RX_ENDPOINT	6
#define CDC2_TX_ENDPOINT	7
#define CDC2_ACM_SIZE		16
#define CDC2_RX_SIZE		64
#define CDC2_TX_SIZE		64
#define ENDPOINT2_CONFIG	ENDPOINT_TRANSMIT_ONLY
#define ENDPOINT3_CONFIG	ENDPOINT_RECEIVE_ONLY
#define ENDPOINT4_CONFIG	ENDPOINT_TRANSMIT_ONLY
#define ENDPOINT5_CONFIG	ENDPOINT_TRANSMIT_ONLY
#define ENDPOINT6_CONFIG	ENDPOINT_RECEIVE_ONLY
#define ENDPOINT7_CONFIG	ENDPOINT_TRANSMIT_ONLY
#define FLIGHTSIM_INTERFACE	4	// Flight Sim Control
#define FLIGHTSIM_TX_ENDPOINT	8
#define FLIGHTSIM_TX_SIZE	64
#define FLIGHTSIM_TX_INTERVAL	1
#define FLIGHTSIM_RX_ENDPOINT	9
#define FLIGHTSIM_RX_SIZE	64
#define FLIGHTSIM_RX_INTERVAL	1
#define ENDPOINT8_CONFIG	ENDPOINT_TRANSMIT_ONLY
#define ENDPOINT9_CONFIG	ENDPOINT_RECEIVE_ONLY
#else

#pragma error "USB customizing only works for Teensy 3.x or 4.x"
#endif

[jbliesener]

A second commit fixes an issue when receiving short strings (less than 3 characters) from X-Plane. When receiving int or float data, the minimum data length was 10 bytes (1b length, 1b command, 2b id, 1b type, 1b pad, 4b data). With variable length data, the minimum data length is just 6.