diff --git a/README.md b/README.md
index 261ef78..a8ffcd4 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,9 @@ product ID or have a K87 layout, so the keyboard is ignored without this plugin.
 
 Copy `Womier_K87_EVision.js` to `%USERPROFILE%\Documents\WhirlwindFX\Plugins\` and restart SignalRGB.
 
+The device settings have a "Key test" option (column or row sweep) to check the LED map,
+and "Low frame-rate mode" in case the keyboard drops frames at full speed.
+
 ## Protocol
 
 - HID interface 1, usage page `0xFF1C`, usage `0x92` (collection 4), 64-byte output reports.
diff --git a/Womier_K87_EVision.js b/Womier_K87_EVision.js
index fbdf8a2..b608cbb 100644
--- a/Womier_K87_EVision.js
+++ b/Womier_K87_EVision.js
@@ -16,13 +16,15 @@ shutdownColor:readonly
 LightingMode:readonly
 forcedColor:readonly
 lowFPS:readonly
+keyTest:readonly
 */
 export function ControllableParameters() {
 	return [
 		{property:"shutdownColor", group:"lighting", label:"Shutdown Color", description: "This color is applied to the device when the System, or SignalRGB is shutting down", min:"0", max:"360", type:"color", default:"#000000"},
 		{property:"LightingMode", group:"lighting", label:"Lighting Mode", description: "Determines where the device's RGB comes from. Canvas will pull from the active Effect, while Forced will override it to a specific color", type:"combobox", values:["Canvas", "Forced"], default:"Canvas"},
 		{property:"forcedColor", group:"lighting", label:"Forced Color", description: "The color used when 'Forced' Lighting Mode is enabled", min:"0", max:"360", type:"color", default:"#009bde"},
-		{property:"lowFPS", group:"lighting", label:"Low frame-rate mode", description: "Sends smaller packets with longer pauses, can improve stability", type:"boolean", default:false},
+		{property:"lowFPS", group:"lighting", label:"Low frame-rate mode", description: "Sends smaller packets with pauses in between, can improve stability", type:"boolean", default:false},
+		{property:"keyTest", group:"lighting", label:"Key test", description: "Sweeps a white line across the keys to check the LED map", type:"combobox", values:["Off", "Column sweep", "Row sweep"], default:"Off"},
 	];
 }
 
@@ -75,6 +77,8 @@ export function Shutdown(SystemSuspending) {
 
 function sendColors(overrideColor) {
 	const RGBData = new Array(LED_SLOTS * 3).fill(0);
+	const [width, height] = Size();
+	const step = Math.floor(Date.now() / 500);
 
 	for (let iIdx = 0; iIdx < vLeds.length; iIdx++) {
 		const [iPxX, iPxY] = vLedPositions[iIdx];
@@ -82,6 +86,10 @@ function sendColors(overrideColor) {
 
 		if (overrideColor) {
 			color = hexToRgb(overrideColor);
+		} else if (keyTest === "Column sweep") {
+			color = iPxX === step % width ? [255, 255, 255] : [0, 0, 0];
+		} else if (keyTest === "Row sweep") {
+			color = iPxY === step % height ? [255, 255, 255] : [0, 0, 0];
 		} else if (LightingMode === "Forced") {
 			color = hexToRgb(forcedColor);
 		} else {
@@ -98,7 +106,6 @@ function sendColors(overrideColor) {
 
 function writeRGBPackage(RGBData) {
 	const bytesToSend = lowFPS ? 48 : 56;
-	const pauseDuration = lowFPS ? 3 : 1;
 
 	for (let offset = 0; offset < RGBData.length; offset += bytesToSend) {
 		const data = RGBData.slice(offset, offset + bytesToSend);
@@ -116,7 +123,9 @@ function writeRGBPackage(RGBData) {
 		packet[2] = (sum >> 8) & 0xFF;
 
 		device.write(packet, 64);
-		device.pause(pauseDuration);
+
+		// device.pause() rounds up to the Windows timer tick (up to ~15 ms), so only pause when asked
+		if (lowFPS) { device.pause(3); }
 	}
 }