option to set mouse sensor angle

firmware/include/config.h

 #define INVERT_MOUSE_X_AXIS false
 #define INVERT_MOUSE_Y_AXIS true
 #define DEFAULT_MOUSE_SENSITIVITY PMW_CPI_TO_SENSE(500)
+#define DEFAULT_MOUSE_ANGLE -30
 
 #define INVERT_SCROLL_X_AXIS false
 #define INVERT_SCROLL_Y_AXIS false

firmware/include/pmw3360.h

 #define PMW_SENSE_TO_CPI(sense) (100 + (sense * 100))
 #define PMW_CPI_TO_SENSE(cpi) ((cpi / 100) - 1)
 
+void pmw_set_angle(int8_t angle);
+int8_t pmw_get_angle(void);
+
 void pmw_print_status(char *buff, size_t len);
 void pmw_dump_data(bool serial);
 

firmware/src/console.c

         println("Trackball Firmware Usage:");
         println("    cpi - print current sensitivity");
         println("  cpi N - set sensitivity");
+        println("  angle - print current angle");
+        println("angle N - set angle");
         println("   pmws - print PMW3360 status");
         println("   pmwf - print PMW3360 frame capture");
         println("   pmwd - print PMW3360 data dump");
             println("setting cpi to 0x%02llX", num);
             pmw_set_sensitivity(num);
         }
+    } else if (strcmp(line, "angle") == 0) {
+        int8_t angle = pmw_get_angle();
+        println("current angle: %d", angle);
+    } else if (str_startswith(line, "angle ")) {
+        const char *num_str = line + 6;
+        intmax_t num = strtoimax(num_str, NULL, 10);
+        if ((num < -128) || (num > 127)) {
+            println("invalid angle %lld, needs to be %d <= cpi <= %d", num, -128, 127);
+        } else {
+            int8_t tmp = num;
+            println("setting angle to %d", tmp);
+            pmw_set_angle(num);
+        }
     } else if (strcmp(line, "reset") == 0) {
         reset_to_main();
     } else if ((strcmp(line, "stats") == 0) || (strcmp(line, "data") == 0)) {

firmware/src/pmw3360.c

     }
 }
 
+static void pmw_irq_start(void) {
+    gpio_set_irq_enabled(PMW_MOTION_PIN, GPIO_IRQ_LEVEL_LOW, true);
+}
+
+static void pmw_irq_stop(void) {
+    gpio_set_irq_enabled(PMW_MOTION_PIN, GPIO_IRQ_LEVEL_LOW, false);
+}
+
 void pmw_set_sensitivity(uint8_t sens) {
     if (sens > 0x77) {
         debug("invalid sense, clamping (0x%X > 0x77)", sens);
         sens = 0x77;
     }
 
+    pmw_irq_stop();
+
     pmw_write_register(REG_CONFIG1, sens);
     pmw_write_register(REG_CONFIG5, sens);
+
+    pmw_irq_start();
 }
 
 uint8_t pmw_get_sensitivity(void) {
+    pmw_irq_stop();
+
     uint8_t sense_y = pmw_read_register(REG_CONFIG1);
     uint8_t sense_x = pmw_read_register(REG_CONFIG5);
     if (sense_y != sense_x) {
         debug("sensitivity differs for x (0x%02X) and y (0x%02X). resetting.", sense_x, sense_y);
         pmw_write_register(REG_CONFIG5, sense_y);
     }
+
+    pmw_irq_start();
     return sense_y;
 }
 
-static void pmw_irq_start(void) {
-    gpio_set_irq_enabled(PMW_MOTION_PIN, GPIO_IRQ_LEVEL_LOW, true);
+void pmw_set_angle(int8_t angle) {
+    pmw_irq_stop();
+
+    uint8_t tmp = *((uint8_t *)(&angle));
+    pmw_write_register(REG_ANGLE_TUNE, tmp);
+
+    pmw_irq_start();
 }
 
-static void pmw_irq_stop(void) {
-    gpio_set_irq_enabled(PMW_MOTION_PIN, GPIO_IRQ_LEVEL_LOW, false);
+int8_t pmw_get_angle(void) {
+    pmw_irq_stop();
+
+    uint8_t tmp = pmw_read_register(REG_ANGLE_TUNE);
+    int8_t angle = *((int8_t *)(&tmp));
+
+    pmw_irq_start();
+    return angle;
 }
 
 static void pmw_irq_init(void) {
     // Set lift-detection threshold to 3mm (max)
     pmw_write_register(REG_LIFT_CONFIG, 0x03);
 
+    pmw_set_angle(DEFAULT_MOUSE_ANGLE);
+
     pmw_irq_init();
 
     return 0;