From 10148fa9cf5bce7e51ecc608a7e31629b90535ea Mon Sep 17 00:00:00 2001
From: David Lechner <david@pybricks.com>
Date: Wed, 23 Jun 2021 12:31:19 -0500
Subject: [PATCH] ble-uart: decode PnP ID if it exists

---
 src/ble-device-info-service/protocol.ts | 37 +++++++++++++++++++++++++
 src/ble-uart/sagas.ts                   | 32 +++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/src/ble-device-info-service/protocol.ts b/src/ble-device-info-service/protocol.ts
index f1517a86..b94296ae 100644
--- a/src/ble-device-info-service/protocol.ts
+++ b/src/ble-device-info-service/protocol.ts
@@ -13,3 +13,40 @@ export const firmwareRevisionStringUUID = 0x2a26;
 
 /** Software Revision String characteristic UUID. */
 export const softwareRevisionStringUUID = 0x2a28;
+
+/** PnP ID characteristic UUID. */
+export const pnpIdUUID = 0x2a50;
+
+/**
+ * Parameters for the PnP ID characteristic vendor ID source field.
+ */
+export enum PnpIdVendorIdSource {
+    /** The vendor ID was assigned by the Bluetooth SIG. */
+    BluetoothSig = 1,
+    /** The vendor and product IDs were assigned by the USB implementors forum. */
+    UsbImpForum = 2,
+}
+
+/**
+ * Decoded data from the PnP ID characteristic.
+ */
+export type PnpId = {
+    vendorIdSource: PnpIdVendorIdSource;
+    vendorId: number;
+    productId: number;
+    productVersion: number;
+};
+
+/**
+ * Decodes data read from the PnP ID characteristics.
+ * @param data The data read from the characteristic.
+ * @returns The decoded data.
+ */
+export function decodePnpId(data: DataView): PnpId {
+    return {
+        vendorIdSource: data.getUint8(0),
+        vendorId: data.getUint16(1, true),
+        productId: data.getUint16(3, true),
+        productVersion: data.getUint16(5, true),
+    };
+}
diff --git a/src/ble-uart/sagas.ts b/src/ble-uart/sagas.ts
index a16e0d2c..acf1ab40 100644
--- a/src/ble-uart/sagas.ts
+++ b/src/ble-uart/sagas.ts
@@ -16,8 +16,11 @@ import {
     takeMaybe,
 } from 'typed-redux-saga/macro';
 import {
+    PnpId,
+    decodePnpId,
     serviceUUID as deviceInfoServiceUUID,
     firmwareRevisionStringUUID,
+    pnpIdUUID,
     softwareRevisionStringUUID,
 } from '../ble-device-info-service/protocol';
 import {
@@ -45,6 +48,7 @@ import {
 } from '../ble/actions';
 import { BleConnectionState } from '../ble/reducers';
 import { RootState } from '../reducers';
+import { hex } from '../utils';
 import {
     BleUartActionType,
     BleUartWriteAction,
@@ -229,6 +233,34 @@ function* connect(_action: BleDeviceConnectAction): Generator {
     // TODO: verify that minimum protocol version is met
     console.log(`Pybricks protocol version: ${protocolVersion}`);
 
+    let pnpIdChar: BluetoothRemoteGATTCharacteristic | undefined = undefined;
+    try {
+        pnpIdChar = yield* call([deviceInfoService, 'getCharacteristic'], pnpIdUUID);
+    } catch (err) {
+        console.warn(
+            'PnP ID characteristic requires Pybricks firmware v3.1.0a1 or later',
+        );
+    }
+
+    if (pnpIdChar) {
+        let pnpId: PnpId;
+        try {
+            pnpId = decodePnpId(yield* call([pnpIdChar, 'readValue']));
+        } catch (err) {
+            server.disconnect();
+            yield* takeMaybe(disconnectChannel);
+            yield* put(didFailToConnect({ reason: Reason.Unknown, err }));
+            return;
+        }
+
+        console.log(
+            `Vendor: ${hex(pnpId.vendorId, 4)}, Product: ${hex(
+                pnpId.productId,
+                4,
+            )}, Version: ${hex(pnpId.productVersion, 4)}`,
+        );
+    }
+
     let pybricksService: BluetoothRemoteGATTService;
     try {
         pybricksService = yield* call(