AT+CGLA=? not supported on EM7590 and AT+CCHO returns error

IoT Modules
1

Hi,

I am using an EM7590 along with a eSIM (in plastic SIM format) and running a lpac (GitHub - estkme-group/lpac: C-based eUICC LPA) on linux (ubuntu 22.04).

lpac works with the same exact sim, same code with MC7455.

I see two issues right now:

  1. AT+CGLA=? return ERROR instead of OK, I bypassed this code as it is a check to see if the modem supports AT+CGLA=?
    2.AT+CCHO=“A0000005591010FFFFFFFF8900000100”
    Returns: +CME ERROR: 323
    This command is a fixed string that LPAC sends to open a logic channel to the eUICC

I am running the latest generic FW, see ATI output:
Manufacturer: Sierra Wireless
Model: EM7590
Revision: SWIX12C_02.02.03.00 2024/01/29 23:36:42
SVN: 04
IMEI: 357999720045394
FSN: DX3133035305G1
TS.25: 2024.1.1

AT+CCID? returns the right CCID so I assume the modem is able to talk with the SIM

Per the AT commands reference for EM7590 both AT+CGLA and AT+CCHO should be supported but something is wrong:
https://source.sierrawireless.com/resources/airprime/minicard/75xx/em7590/airprime-em7590-at-command-reference/#sthash.PneIKKum.dpbs

Please advise how to fix it, is there a special mode/command that needs to be entered to enable SIM access?

2

Hi @uriel,

can you please check the AT!CUSTOM? output whether somebody enabled PCSCDISABLE flags (default should be 0)? This might explain the observed behaviour.

Regards,
Reinhard

3

AT!CUSTOM?
!CUSTOM:
“SIMLPA” 0x01
“UIM2ENABLE” 0x01
“USBSERIALENABLE” 0x02
“GPSENABLE” 0x01

I don’t see PCSCDISABLE but maybe it is because of SIMLPA? what is that flag?

4

@uriel,
SIMLPA looks like a new AT!CUSTOM option with EM759x devices.
Newer devices (from other UE vendors) provide eSIM-related AT commands to read the EID or list the profiles and having it enabled may interfere with lpac’s use of logical channels or acess to certain AIDs.

It may help to set it to 0 with AT!CUSTOM="SIMLPA",0 and retry with lpac after resetting or power-cycling the EM7590.

Regards,
Reinhard

5

Trying to set SIMLPA to 0 with the command you have given just returns ERROR.

power cycling doesn’t help either.

6

Running:

AT!ENTERCND="A710"

Allows me to run

AT!CUSTOM="SIMLPA",0

Then running AT!CUSTOM after AT!RESET shows:

AT!CUSTOM?
!CUSTOM:
                "UIM2ENABLE"         0x01
                "USBSERIALENABLE"    0x02
                "GPSENABLE"          0x01


OK

But still running AT+CGLA=? returns an ERROR.

But I manage now to run AT+CCHO so it seems AT+CGLA=? isn’t supported at all?

I am now going to try the full sequence

7

With this fix I can report that everything works!

So in short:

  1. AT+CGLA=? isn’t supported (Please fix your documentation)
  2. SIMLPA doesn’t allow AT+CCHO to work
  3. Disabling SIMLPA requires AT!ENTERCND=“A710” followed by AT!CUSTOM=“SIMLPA”,0
  4. After that AT+CCHO and AT+CGLA= (but not AT+CGLA=?) works

I can confirm that with this instructions and some hacking into lpac to make it not check for AT+CGLA=? I can list the profiles in the eSIM I use