| 1 | // WebSerial transport for the EBB (USB CDC serial; Chrome/Edge/Opera).
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| 2 |
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| 3 | // EiBotBoard USB IDs (Microchip VID, Evil Mad Scientist PID).
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| 4 | export const EBB_USB_FILTER = { usbVendorId: 0x04d8, usbProductId: 0xfd92 };
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| 5 |
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| 6 | export function webSerialSupported() {
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| 7 | return typeof navigator !== 'undefined' && 'serial' in navigator;
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| 8 | }
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| 9 |
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| 10 | export class WebSerialTransport {
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| 11 | constructor(port) {
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| 12 | this.port = port;
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| 13 | this.reader = null;
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| 14 | this.writer = null;
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| 15 | this.buffer = '';
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| 16 | this.decoder = new TextDecoder();
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| 17 | this.encoder = new TextEncoder();
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| 18 | this.pending = null; // In-flight reader.read() promise, kept across timeouts
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| 19 | }
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| 20 |
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| 21 | /** Prompt the user to pick a NextDraw. Must be called from a user gesture. */
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| 22 | static async request() {
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| 23 | const port = await navigator.serial.requestPort({ filters: [EBB_USB_FILTER] });
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| 24 | return new WebSerialTransport(port);
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| 25 | }
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| 26 |
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| 27 | /** Previously-authorized NextDraws, available without a prompt. */
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| 28 | static async authorized() {
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| 29 | const ports = await navigator.serial.getPorts();
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| 30 | return ports
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| 31 | .filter((p) => {
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| 32 | const info = p.getInfo();
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| 33 | return info.usbVendorId === EBB_USB_FILTER.usbVendorId && info.usbProductId === EBB_USB_FILTER.usbProductId;
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| 34 | })
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| 35 | .map((p) => new WebSerialTransport(p));
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| 36 | }
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| 37 |
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| 38 | async open() {
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| 39 | if (!this.port.readable) await this.port.open({ baudRate: 115200 });
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| 40 | this.reader = this.port.readable.getReader();
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| 41 | this.writer = this.port.writable.getWriter();
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| 42 | }
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| 43 |
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| 44 | async close() {
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| 45 | try {
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| 46 | if (this.reader) {
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| 47 | await this.reader.cancel().catch(() => {});
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| 48 | this.reader.releaseLock();
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| 49 | }
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| 50 | if (this.writer) {
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| 51 | await this.writer.close().catch(() => {});
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| 52 | this.writer.releaseLock();
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| 53 | }
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| 54 | } finally {
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| 55 | this.reader = null;
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| 56 | this.writer = null;
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| 57 | this.pending = null;
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| 58 | await this.port.close().catch(() => {});
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| 59 | }
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| 60 | }
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| 61 |
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| 62 | async write(text) {
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| 63 | await this.writer.write(this.encoder.encode(text));
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| 64 | }
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| 65 |
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| 66 | /** Discard anything already received. */
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| 67 | async clearInput() {
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| 68 | this.buffer = '';
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| 69 | // Drain whatever arrives within a short window.
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| 70 | while ((await this.readChunk(20)) != null) this.buffer = '';
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| 71 | }
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| 72 |
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| 73 | /** Resolve with the next chunk of text, or null after timeoutMs. */
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| 74 | async readChunk(timeoutMs) {
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| 75 | if (!this.pending) {
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| 76 | this.pending = this.reader.read().then((r) => {
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| 77 | this.pending = null;
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| 78 | if (r.done) throw new Error('Serial port closed');
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| 79 | return this.decoder.decode(r.value, { stream: true });
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| 80 | });
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| 81 | }
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| 82 | let timer;
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| 83 | const timeout = new Promise((resolve) => { timer = setTimeout(() => resolve(null), timeoutMs); });
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| 84 | try {
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| 85 | return await Promise.race([this.pending, timeout]);
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| 86 | } finally {
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| 87 | clearTimeout(timer);
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| 88 | }
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| 89 | }
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| 90 |
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| 91 | /** Next line without its terminator, or '' on timeout (like pyserial readline). */
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| 92 | async readLine(timeoutMs = 1000) {
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| 93 | const deadline = performance.now() + timeoutMs;
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| 94 | for (;;) {
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| 95 | const nl = this.buffer.indexOf('\n');
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| 96 | if (nl >= 0) {
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| 97 | const line = this.buffer.slice(0, nl + 1);
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| 98 | this.buffer = this.buffer.slice(nl + 1);
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| 99 | return line;
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| 100 | }
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| 101 | const remaining = deadline - performance.now();
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| 102 | if (remaining <= 0) return '';
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| 103 | const chunk = await this.readChunk(remaining);
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| 104 | if (chunk == null) return '';
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| 105 | this.buffer += chunk;
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| 106 | }
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| 107 | }
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| 108 | }
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