USB Touchscreen basic functions (work in progress)

teensy3/WProgram.h

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

teensy3/usb_touch.c

 #ifdef MULTITOUCH_INTERFACE // defined by usb_dev.h -> usb_desc.h
 #if F_CPU >= 20000000
 
-void usb_touchscreen_press(uint8_t finger, uint32_t x, uint32_t y, uint32_t pressure)
+static uint8_t  prev_id=0;
+static uint8_t  pressure[MULTITOUCH_FINGERS];
+static uint8_t  contactid[MULTITOUCH_FINGERS];
+static uint16_t xpos[MULTITOUCH_FINGERS];
+static uint16_t ypos[MULTITOUCH_FINGERS];
+
+static uint8_t  scan_state=0;
+static uint8_t  scan_remain=0; // number of finger to left to transmit on this scan
+static uint8_t  scan_index=0;  // index of next (possible) finger to transmit
+static uint8_t  scan_pressure[MULTITOUCH_FINGERS];
+static uint16_t scan_timestamp;
+
+
+void usb_touchscreen_press(uint8_t finger, uint32_t x, uint32_t y, uint32_t press)
 {
-	// TODO...
+	uint8_t id;
+
+	if (finger >= MULTITOUCH_FINGERS) return;
+	press >>= 1;
+	if (press > 127) press = 127;
+	if (x > 32767) x = 32767;
+	if (y > 32767) y = 32767;
+	if (pressure[finger] == 0) {
+		id = prev_id + 1;
+		if (id == 0) id = 1;
+		prev_id = id;
+		contactid[finger] = id;
+	}
+	xpos[finger] = x;
+	ypos[finger] = y;
+	pressure[finger] = (press << 1) | 1;
 }
 
 void usb_touchscreen_release(uint8_t finger)
 {
-	// TODO...
+	if (finger >= MULTITOUCH_FINGERS) return;
+	pressure[finger] = 0;
 }
 
+// touch report
+//  0: on/off + pressure
+//  1: contact id
+//  2: X lsb
+//  3: X msb
+//  4: Y lsb
+//  5: Y msb
+//  6: scan time lsb
+//  7: scan time msb
+//  8: contact count
+
+static int usb_touchscreen_transmit(int index, int count)
+{
+	usb_packet_t *tx_packet;
+	tx_packet = usb_malloc();
+	if (tx_packet == NULL) return 0;
+	*(tx_packet->buf + 0) = pressure[index];
+	*(tx_packet->buf + 1) = contactid[index];
+	*(tx_packet->buf + 2) = xpos[index];
+	*(tx_packet->buf + 3) = xpos[index] >> 8;
+	*(tx_packet->buf + 4) = ypos[index];
+	*(tx_packet->buf + 5) = ypos[index] >> 8;
+	*(tx_packet->buf + 6) = scan_timestamp;
+	*(tx_packet->buf + 7) = scan_timestamp >> 8;
+	*(tx_packet->buf + 8) = count;
+	tx_packet->len = 9;
+	usb_tx(MULTITOUCH_ENDPOINT, tx_packet);
+	delayMicroseconds(20);
+	return 1;
+}
+
+
 // Called by the start-of-frame interrupt.
 //
 void usb_touchscreen_update_callback(void)
 {
-	// TODO...
+	int i, r, count=0;
+
+	digitalWriteFast(13, HIGH);
+	if (scan_state == 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;
+		}
+		// copy the pressure data - whether each finger is
+		// in contact at the moment of this "scan"
+		memcpy(scan_pressure, pressure, MULTITOUCH_FINGERS);
+		for (i=0; i < MULTITOUCH_FINGERS; i++) {
+			if (scan_pressure[i] > 0) count++;
+		}
+		if (count > 0) {
+			scan_remain = count;
+			scan_index = 0;
+			scan_timestamp = millis() * 10;
+		} else {
+			scan_remain = 0;
+		}
+	}
+	if (scan_remain > 0) {
+		for (i = scan_index; i < MULTITOUCH_FINGERS; i++) {
+			if (scan_pressure[i] > 0) break;
+		}
+		r = usb_touchscreen_transmit(i, (scan_state == 0) ? scan_remain : 0);
+		if (!r) return;
+		scan_index = i + 1;
+		scan_remain--;
+	}
+	if (++scan_state >= MULTITOUCH_ENDPOINT) {
+		scan_state = 0;
+	}
+	delayMicroseconds(10);
+	digitalWriteFast(13, LOW);
 }
 
+
 #endif // F_CPU
 #endif // MULTITOUCH_INTERFACE