Driver confusion

[szmarci]

Hi!

I am trying to write a driver for the MPU9250 accelerometer & gyroscope module based on the existing DA213 driver.
I adjusted the code based on some sample and the datasheet of the chip:

export class MPU9250Driver extends I2CDriver implements AccelerometerDriver {
  async readSample() {
      const data: Buffer = await this.readRegBuf(0x3B, 6)
      const x = convert(data[0], data[1])
      const y = convert(data[2], data[3])
      const z = convert(data[4], data[5])
      return [x,y,z]
  }
  
  subscribe(cb: (sample: Vector3D) => Promise<void>): void {
      const _this = this
      setInterval(async () => {
          const s = await _this.readSample()
          await cb(s as Vector3D)
      }, 50)
  }
}

import { startAccelerometer } from "@devicescript/drivers"

export class MPU9250 {
  async startAccelerometer() {
      const driver = new MPU9250Driver()
      await driver.init();
      const acc = await startAccelerometer(driver, {})
      return acc
  }
}

main.ts:

import { MPU9250 } from "./mpu9250";

const accelerometer = new MPU9250();
const instance = await accelerometer.startAccelerometer()

instance.reading.subscribe(v => {
    console.log("from accelerometer client", v)
})

When I run this code the subscribe method in MPU9250Driver class is called by AccelerometerServer. Apparently this supposed to seed the data here, which it does btw:

However the console.log in main.ts subscribe callback is not triggered until I add this:

import { Accelerometer } from "@devicescript/core";
import { MPU9250 } from "./mpu9250";

const accelerometer = new MPU9250();
+const instance = await accelerometer.startAccelerometer()

const a = new Accelerometer('accelerometer2');

instance.reading.subscribe(v => {
    console.log("from accelerometer client", v)
})

Then it starts to log, which is weird to me because this const a object just hangs in nowhere.
Also this is changed from all clients bound to missing servers:

Read the documentation about this client & server architecture, but it still does not click to me.
Can anyone of you explain it to me?

Thank you!

[pelikhan]

The startAccelerometer returns a client that is already bound to your server so you don't need the "const a .... " line. You can simply remove it.

As for testing on hardware on the pico, make sure to configure the I2C pins you plan to use (see https://microsoft.github.io/devicescript/developer/board-configuration#i2c ). You're close to get it to work.

[pelikhan]

The simulation was broken... now the client binding bug appears in hardware and sim :)

There's currently a bug in the client role assignment that seems to occur when one instantiates the client in an class instance function. Surprisingly, move the startAccelerometer to a function fixes the issue:

export async function startMPU9250() {
  const driver = new MPU9250Driver()
  await driver.init();
  const acc = await startAccelerometer(driver, {})
  return acc
}

[pelikhan]

see szmarci/devicescript_test#1

[szmarci]

Ah I see, this binding it is.
It also works when you change the class method to an arrow function:

export class MPU9250 {
    startAccelerometer = async () => {
        const driver = new MPU9250Driver()
        await driver.init();
        const acc = await startAccelerometer(driver, {})
        return acc
    }
}

[mmoskal]

The issue should be now fixed in v2.15.20