fix: address overflow and persistance bugs with filter config

firmware/src/commands.c

@@ -328,9 +328,10 @@ static void handle_ir(int argc, char *argv[])
 static void handle_filter(int argc, char *argv[])
 {
     const char *usage = "Usage: filter <first> <second> [interval]\n"
-                        "    first: First iteration [0..3]\n"
-                        "   second: Second iteration [0..3]\n"
-                        " interval: Interval of second iterations [0..7]\n";
+                        "Adjusts MPR121 noise filtering parameters. See datasheets for more details.\n"
+                        "    first:    First Filter Iterations  (FFI) [0..3]\n"
+                        "    second:   Second Filter Iterations (SFI) [0..3]\n"
+                        "    interval: Electode Sample Interval (ESI) [0..7]\n";
     if ((argc < 2) || (argc > 3)) {
         printf(usage);
         return;
@@ -348,9 +349,7 @@ static void handle_filter(int argc, char *argv[])
         printf(usage);
         return;
     }
-
-    chu_cfg->sense.filter = (ffi << 6) | (sfi << 4) | intv;
-
+    chu_cfg->sense.filter = (uint8_t)((ffi << 6) | (sfi << 4) | intv );
     slider_update_config();
     config_changed();
     disp_sense();

firmware/src/config.c

@@ -61,8 +61,11 @@ static void config_loaded()
         chu_cfg->tof = default_cfg.tof;
         config_changed();
     }
-    if ((chu_cfg->sense.filter & 0x0f) > 3 ||
-        ((chu_cfg->sense.filter >> 4) & 0x0f) > 3) {
+    if (
+        ((chu_cfg->sense.filter & 0x07) > 7) ||
+        ((chu_cfg->sense.filter >> 6) > 3) ||
+        (((chu_cfg->sense.filter >> 4) & 0x03) > 3)
+       ) {
         chu_cfg->sense.filter = default_cfg.sense.filter;
         config_changed();
     }

firmware/src/config.h

@@ -28,7 +28,7 @@ typedef struct __attribute__((packed)) {
         uint8_t pitch;
     } tof;
     struct {
-        int8_t filter;
+        uint8_t filter;
         int8_t global;
         uint8_t debounce_touch;
         uint8_t debounce_release;