Add USB touchscreen (work in progress) for Teensy 4.0

teensy4/WProgram.h

 //#include "usb_flightsim.h"
 //#include "usb_mtp.h"
 //#include "usb_audio.h"
-//#include "usb_touch.h"
+#include "usb_touch.h"
 //#include "usb_undef.h" // do not allow usb_desc.h stuff to leak to user programs
 
 #include "WCharacter.h"

teensy4/usb.c

 #include "usb_keyboard.h"
 #include "usb_mouse.h"
 #include "usb_joystick.h"
+#include "usb_touch.h"
 #include "core_pins.h" // for delay()
 #include "avr/pgmspace.h"
 #include <string.h>
 		#if defined(JOYSTICK_INTERFACE)
 		usb_joystick_configure();
 		#endif
+		#if defined(MULTITOUCH_INTERFACE)
+		usb_touchscreen_configure();
+		#endif
 		endpoint0_receive(NULL, 0, 0);
 		return;
 	  case 0x0880: // GET_CONFIGURATION

teensy4/usb_desc.h

   #define NUM_ENDPOINTS         5
   #define NUM_INTERFACE		4
   #define SEREMU_INTERFACE      1	// Serial emulation
-  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_ENDPOINT    2
   #define SEREMU_TX_SIZE        64
   #define SEREMU_TX_INTERVAL    1
   #define SEREMU_RX_ENDPOINT    2
   #define MULTITOUCH_ENDPOINT   5
   #define MULTITOUCH_SIZE       8
   #define MULTITOUCH_FINGERS    10
-  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSMIT_ONLY
-  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
-  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSMIT_ONLY
-  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSMIT_ONLY
-  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_INTERRUPT + ENDPOINT_TRANSMIT_INTERRUPT
+  #define ENDPOINT3_CONFIG      ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
+  #define ENDPOINT5_CONFIG      ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
 
 #elif defined(USB_HID_TOUCHSCREEN)
   #define VENDOR_ID		0x16C0
   #define NUM_ENDPOINTS         6
   #define NUM_INTERFACE		5
   #define SEREMU_INTERFACE      2	// Serial emulation
-  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_ENDPOINT    2
   #define SEREMU_TX_SIZE        64
   #define SEREMU_TX_INTERVAL    1
   #define SEREMU_RX_ENDPOINT    2
   #define MULTITOUCH_ENDPOINT   5
   #define MULTITOUCH_SIZE       8
   #define MULTITOUCH_FINGERS    10
-  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSMIT_ONLY
-  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
-  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSMIT_ONLY
-  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSMIT_ONLY
-  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSMIT_ONLY
-  #define ENDPOINT6_CONFIG	ENDPOINT_TRANSMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_INTERRUPT + ENDPOINT_TRANSMIT_INTERRUPT
+  #define ENDPOINT3_CONFIG      ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
+  #define ENDPOINT5_CONFIG      ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
+  #define ENDPOINT6_CONFIG      ENDPOINT_RECEIVE_UNUSED + ENDPOINT_TRANSMIT_INTERRUPT
 
 #elif defined(USB_MIDI)
   #define VENDOR_ID		0x16C0

teensy4/usb_touch.c

+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2019 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "usb_dev.h"
+#include "usb_touch.h"
+#include "core_pins.h" // for millis()
+#include <string.h> // for memcpy()
+#include "avr/pgmspace.h" // for PROGMEM, DMAMEM, FASTRUN
+#include "debug/printf.h"
+#include "core_pins.h"
+
+
+#ifdef MULTITOUCH_INTERFACE // defined by usb_dev.h -> usb_desc.h
+
+static uint8_t  prev_id=0;
+static uint8_t  scan_index=0;
+static uint8_t  scan_count=0;
+static uint8_t  contactid[MULTITOUCH_FINGERS];
+static uint8_t  pressure[MULTITOUCH_FINGERS];
+static uint16_t xpos[MULTITOUCH_FINGERS];
+static uint16_t ypos[MULTITOUCH_FINGERS];
+static uint16_t scan_timestamp;
+
+#define TX_NUM     20
+#define TX_BUFSIZE 32
+static transfer_t tx_transfer[TX_NUM] __attribute__ ((used, aligned(32)));
+DMAMEM static uint8_t txbuffer[TX_NUM * TX_BUFSIZE] __attribute__ ((aligned(32)));
+static uint8_t tx_head=0;
+#if MULTITOUCH_SIZE > TX_BUFSIZE
+#error "Internal error, transmit buffer size is too small for touchscreen endpoint"
+#endif
+
+
+void usb_touchscreen_configure(void)
+{
+	memset(tx_transfer, 0, sizeof(tx_transfer));
+	tx_head = 0;
+	usb_config_tx(MULTITOUCH_ENDPOINT, MULTITOUCH_SIZE, 0, NULL);
+	// TODO: need to cause usb_touchscreen_update_callback to be run on SOF
+}
+
+
+void usb_touchscreen_press(uint8_t finger, uint32_t x, uint32_t y, uint32_t press)
+{
+	if (finger >= MULTITOUCH_FINGERS) return;
+	if (press > 255) press = 255;
+	if (x > 32767) x = 32767;
+	if (y > 32767) y = 32767;
+	__disable_irq();
+	if (pressure[finger] == 0 && press > 0) {
+		// Begin a new finger touch, assign a
+		// new Contact Identifier (usage 0x51)
+		uint8_t id = prev_id + 1;
+		if (id == 0 || id > 127) id = 1;
+		prev_id = id;
+		contactid[finger] = (id << 1) | 1;
+	}
+	xpos[finger] = x;
+	ypos[finger] = y;
+	pressure[finger] = press;
+	__enable_irq();
+}
+
+// User should allow at least 12 ms after release before starting a
+// new touch with press, in case the host's driver does not properly
+// parse a change in contact identifier to mean a new touch.
+
+void usb_touchscreen_release(uint8_t finger)
+{
+	if (finger >= MULTITOUCH_FINGERS) return;
+	pressure[finger] = 0;
+}
+
+
+static int transmit(const uint8_t *data)
+{
+	if (!usb_configuration) return 0;
+	uint32_t head = tx_head;
+	transfer_t *xfer = tx_transfer + head;
+	uint32_t status = usb_transfer_status(xfer);
+	if ((status & 0x80)) return 0;
+	if (status & 0x68) {
+		// TODO: what if status has errors???
+	}
+	uint8_t *buffer = txbuffer + head * TX_BUFSIZE;
+	memcpy(buffer, data, MULTITOUCH_SIZE);
+	usb_prepare_transfer(xfer, buffer, MULTITOUCH_SIZE, 0);
+	arm_dcache_flush_delete(buffer, TX_BUFSIZE);
+	usb_transmit(MULTITOUCH_ENDPOINT, xfer);
+	if (++head >= TX_NUM) head = 0;
+	tx_head = head;
+	return 1;
+}
+
+// touch report
+//  0: contact id + on/off
+//  1: pressure
+//  2: X lsb
+//  3: X msb
+//  4: Y lsb
+//  5: Y msb
+//  6: scan time lsb
+//  7: scan time msb
+
+
+// Called by the start-of-frame interrupt.
+//
+void usb_touchscreen_update_callback(void)
+{
+	// TODO: if 480 speed, run only every 8th time
+
+	if (scan_index == 0) {
+		if (usb_tx_packet_count(MULTITOUCH_ENDPOINT) > 1) {
+			// wait to begin another scan if if more than
+			// one prior packet remains to transmit
+			return;
+		}
+		scan_timestamp = millis() * 10;
+		scan_count = 0;
+	}
+	while (scan_index < MULTITOUCH_FINGERS) {
+		uint32_t press = pressure[scan_index];
+		uint32_t id = contactid[scan_index];
+		if (id) {
+			if (press == 0) {
+				// End a finger touch.  One final packet sent
+				// with same Contact Identifier (usage 0x51)
+				// and Tip Switch (usage 0x42) = zero
+				id &= 0xFE;
+				contactid[scan_index] = 0;
+			}
+			uint8_t buffer[MULTITOUCH_SIZE]; // MULTITOUCH_SIZE = 8
+			buffer[0] = id;
+			buffer[1] = press;
+			buffer[2] = xpos[scan_index];
+			buffer[3] = xpos[scan_index] >> 8;
+			buffer[4] = ypos[scan_index];
+			buffer[5] = ypos[scan_index] >> 8;
+			buffer[6] = scan_timestamp;
+			buffer[7] = scan_timestamp >> 8;
+			if (transmit(buffer)) scan_index++;
+			return;
+		}
+		scan_index++;
+	}
+	if (++scan_count >= MULTITOUCH_FINGERS) {
+		// when done early, wait to restart another scan
+		scan_index = 0;
+	}
+}
+
+
+#endif // MULTITOUCH_INTERFACE

teensy4/usb_touch.h

+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef USBtouchscreen_h_
+#define USBtouchscreen_h_
+
+#include "usb_desc.h"
+
+#if defined(MULTITOUCH_INTERFACE)
+
+#include <inttypes.h>
+
+// C language implementation
+#ifdef __cplusplus
+extern "C" {
+#endif
+void usb_touchscreen_configure(void);
+void usb_touchscreen_press(uint8_t finger, uint32_t x, uint32_t y, uint32_t pressure);
+void usb_touchscreen_release(uint8_t finger);
+void usb_touchscreen_update_callback(void);
+extern volatile uint8_t usb_configuration;
+#ifdef __cplusplus
+}
+#endif
+
+// C++ interface
+#ifdef __cplusplus
+class usb_touchscreen_class
+{
+        public:
+        void begin(void) { }
+        void end(void) { }
+	void press(uint8_t finger, uint32_t x, uint32_t y, uint32_t pressure=128) {
+		usb_touchscreen_press(finger, x, y, pressure);
+	}
+	void release(uint8_t finger) {
+		usb_touchscreen_release(finger);
+	}
+};
+extern usb_touchscreen_class TouchscreenUSB;
+
+#endif // __cplusplus
+
+#endif // MULTITOUCH_INTERFACE
+
+#endif // USBtouchscreen_h_
+