I2C error Is there a way to thow and catch this error?

[espruino-discuss]

Posted at 2017-06-12 by ClearMemory041063

The error message

Uncaught InternalError: Timeout on I2C Read Receive

The usual suspect are pull up resistors

Other causes

You send a command via I2C that causes the device to require a delay before it is ready to talk I2C again.
Examples for the BNO055 are reset, change clock between internal and external

One solution is to use a callback

Is there a way to throw and catch the error and then try again N times or until the error clears?

function start(){
// define the I2C connection
 I2C3.setup({ scl :A8, sda: B4} );
// define the bus address of the BNO055 chip
 var BusAddress= 0x28;//If ADR pin at 3V 0x29
//load the BMO055 module  
 W=require("BNO055").connect(I2C3,BusAddress,function(){

// set the BNO055 clock to external using a callback funtion
W.External_Clk(1,function(){

//the callback code goes here
});//end set external clock 
 });//end require
}//end start

The external clock function with callback

BNO055.prototype.External_Clk=function(a,callback){
 this.selectPage(0);
 if(a)
 this.WriteByte(this.Page0Regs.SYS_TRIGGER,0x80);
 else
 this.WriteByte(this.Page0Regs.SYS_TRIGGER,0x00);
setTimeout(function () {
   callback();
}, 50);
};

[gfwilliams]

Posted at 2017-06-12 by @gfwilliams

If you do:

try {
  I2C3.readFrom(...);
} catch (e) {
  console.log("Oops");
}

then it should work? your inability to catch the error might be because your External_Clk function is itself called from a timeout?

Worst case you can use uncaughtException, but that's a bit of a hack :) http://www.espruino.com/Reference#l_process_uncaughtException

[espruino-discuss]

Posted at 2017-06-12 by ClearMemory041063

Thanks @gordon for the prompt reply.
I'll try your suggestions later today.
It may be a bit more complex but that makes it fun. (see snippet)
Send reset or change clock and then catch the error and retry on a subsequent read of a status register using the snippet.

/** Readbyte(BusAddress,SubAddress) */
BNO055.prototype.ReadByte=function(subAddress){
 var data=Uint8Array(1);
 this.i2c.writeTo(this.BusAddress, subAddress);
 data=this.i2c.readFrom(this.BusAddress, 1);
 return data[0];
};//end ReadByte