EM7455 with OC1120 - AT+CSIM error

IoT Modules
1

I’m trying to use the EM7455 with the OPTIGA™ Connect Consumer OC1120 esim chip from infineon connected to sim slot 0. Whenever I try any AT+CSIM command all I get is ERROR.
This doesn’t happen when I use the other sim slot which has a plastic euicc sim card connected to it.

I connected a logic analyzer to the data pin and got the following initial communication:
0x00 0xA4 0x00 0x04 0x02 0xA4 0x3F 0x00 0x61 0x27 0x00 0xC0 0x00 0x00 0x27 0xC0 0x62 0x25 0x82 0x02 0x78 0x21 0x83 0x02 0x3F 0x00 0xA5 0x0B 0x80 0x01 0x71 0x83 0x03 0x0C 0x27 0xBA 0x87 0x01 0x01 0x8A 0x01 0x05 0x8B 0x03 0x2F 0x06 0x01 0xC6 0x06 0x90 0x01 0x80 0x83 0x01 0x0A 0x90 0x00 0x80 0xAA 0x00 0x00 0x07 0xAA 0xA9 0x05 0x81 0x00 0x82 0x01 0x01 0x90 0x00 0x00 0xA4 0x08 0x04 0x02 0xA4 0x2F 0xE2 0x6A 0x82 0x00 0xA4 0x08 0x04 0x02 0xA4 0x2F 0x05 0x6A 0x82 0x00 0xA4 0x08 0x04 0x02 0xA4 0x2F 0xE2 0x6A 0x82 0x80 0x10 0x00 0x00 0x1E 0x10 0x37 0x09 0xE8 0xCE 0x11 0x9C 0x00 0x07 0x9C 0x00 0x00 0x1F 0xE2 0x60 0x00 0x00 0xC3 0xD0 0x00 0x07 0x00 0x01 0x60 0x00 0x50 0x00 0x00 0x00 0x00 0x08 0x90 0x00 0x00 0xA4 0x08 0x04 0x02 0xA4 0x2F 0x00 0x6A 0x82 0x00 0xA4 0x00 0x04 0x02 0xA4 0x3F 0x00 0x61 0x27 0x00 0xC0 0x00 0x00 0x27 0xC0 0x62 0x25 0x82 0x02 0x78 0x21 0x83 0x02 0x3F 0x00 0xA5 0x0B 0x80 0x01 0x71 0x83 0x03 0x0C 0x27 0xBA 0x87 0x01 0x01 0x8A 0x01 0x05 0x8B 0x03 0x2F 0x06 0x01 0xC6 0x06 0x90 0x01 0x80 0x83 0x01 0x0A 0x90 0x00

Afterwards, whenever I try any AT+CSIM command, nothing is sent over the data line.
I tried upgrading to the latest firmware and it didn’t help.
The output of ATI:

ATI
Manufacturer: Sierra Wireless, Incorporated
Model: EM7455
Revision: SWI9X30C_02.38.00.00 rE3F3E55C03AE94 jenkins 2022/01/13 05:16:00
MEID: 35982032135116                                                            
IMEI: 359820321351163                                                           
IMEI SV: 22                                                                     
FSN: LF235106220210                                                             
+GCAP: +CGSM                                                                    
                                                                                
                                                                                
OK
2

Hi @tomerg
Welcome you to our community
Technically, the AT+CSIM command is used to query SIM card information, which can be stored on the physical SIM and not on the eSIM. So when you type AT+CSIM command on the eSIM, it returns an ERROR.

Please share with me specific the AT+CSIM command that you can use on a physical SIM but not on the eSIM.

Thanks,

3

Sure. For example AT+CSIM=14,"00A40004023F00" or even the simple AT+CSIM=? and AT+CSIM? all get the same ERROR response.
Do note the physical SIM I’m comparing to in the second slot is also an eSIM, just in a plastic SIM card form factor.

4

Hi @tomerg,

as can be seen when decoding the T0 data with Wireshark SELECT MF works when issued by the EM7455 but the eSIM does not have EF.ICCID and EF.DIR and is therefore not considered to be valid by the EM7455.

    1   0.000000              -              GSM SIM ISO/IEC 7816-4 SELECT File MF : Response ready, Response length is 39 
    2   0.000001              -              GSM SIM ISO/IEC 7816-4 GET RESPONSE 
    3   0.000002              -              GSM SIM ETSI TS 102.221 TERMINAL CAPABILITY 
    4   0.000003              -              GSM SIM ISO/IEC 7816-4 SELECT /EF.ICCID : Wrong parameters: File not found 
    5   0.000004              -              GSM SIM ISO/IEC 7816-4 SELECT /EF.ELP : Wrong parameters: File not found 
    6   0.000005              -              GSM SIM ISO/IEC 7816-4 SELECT /EF.ICCID : Wrong parameters: File not found 
    7   0.000006              -              GSM SIM ETSI TS 102.221 TERMINAL PROFILE 
    8   0.000007              -              GSM SIM ISO/IEC 7816-4 SELECT /EF.DIR : Wrong parameters: File not found 
    9   0.000008              -              GSM SIM ISO/IEC 7816-4 SELECT File MF : Response ready, Response length is 39 
   10   0.000009              -              GSM SIM ISO/IEC 7816-4 GET RESPONSE

This does not look like a HW issue to me.

Regards,
Reinhard

1 Like