Sending Assisted GNSS (A-GNSS) to Bangle 2 GPS (AT6558)

@Gordon - I wonder if there are any plans to build an App to send
A-GNSS data to the Bangle 2 GPS chip.s Has there been any attempt
to do this.

I found the following if it is any use to you.
I have been unsuccessful so far in sending any CASIC commands to the B2 GPS.

If you go to https://www.icofchina.com
Got to the downloads link
https://www-icofchina-com.translate.goog­/?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en-­GB

Download AGPS.zip

Unzip and there is a file called agps_demo.c
This shows how to download the A-GNSS information data.

Unzip and inside the AGPS folder is a CasicAgns.zip file.
Inside that zip is file called casicAgnsAidIni.c
This file has the following code at the bottom.

	ckSum = 0x010B0038;
	for (i = 0; i < 14; i++)
	{
		ckSum += pDataBuff[i];
	}

	
	aidIniMsg[0] = 0xBA;
	aidIniMsg[1] = 0xCE;
	aidIniMsg[2] = 0x38;		// LENGTH
	aidIniMsg[3] = 0x00;
	aidIniMsg[4] = 0x0B;		// CLASS	ID
	aidIniMsg[5] = 0x01;		// MESSAGE	ID
	
	memcpy(&aidIniMsg[6],  (char*)(&aidIni), 56);
	memcpy(&aidIniMsg[62], (char*)(&ckSum),  4);
	
	return;
}

The code above makes it look like the start of the CHKSUM is calculated as

sum = (msg_id << 24) + (msg_class << 16) ++ (len_byte1 << 8) + (len_byte0)

This is ties in with the statement in the CASIC document.

The calculation of the check value can follow the following algorithm:
ckSum = (id << 24) + (class << 16) + len;
for (i = 0; i <(len / 4); i++)
{
ckSum = ckSum + payload [i];
}

The point is - that it looks like the CASIC command should work on our Bangle 2 GPS chip.
However so far I have been unable to get a response to a basic CFG-PRT command.
See the other thread by @Mark_M
http://forum.espruino.com/conversations/­371336/#comment16328801