Issue Summary:
I am using a Quectel EG915-EU module with two different M2M SIM cards from different service providers:
- Airtel M2M – Works perfectly, no issues.
- BSNL M2M – Causes the module to reset every 20 seconds.
Troubleshooting Steps Taken:
- Tested on multiple boards → The issue is consistent across all.
- Checked power supply (stable 3.7V-4.2V, 2A peak current) → No power-related issues.
- Used AT+CFUN=0 (minimal functionality mode) → No resets occur.
- Checked SIM detection (
AT+CPIN?) → BSNL SIM is detected and ready. - Checked network registration (
AT+CREG?,AT+CGREG?,AT+CEREG?) → It keeps searching (0,2). - Checked signal strength (
AT+CSQ) → Values are in an acceptable range. - Checked network scan (
AT+COPS=?) → BSNL network is listed. - Tried manual registration (
AT+COPS=1,2,"BSNL_MCCMNC") → Still resets. - Disabled automatic reset (
AT+QCFG="reset_mode",0) → No effect. - Checked LTE band configuration (
AT+QCFG="band") → Settings appear correct.
Observations:
- The module resets only with BSNL M2M SIM, but not with Airtel M2M SIM.
- The reset happens approximately every 20 seconds.
- The issue is not hardware-related, as multiple boards behave the same way.
- When setting CFUN=0 (minimal functionality mode), the module does not reset.
Questions:
- What could be causing the module to reset only with BSNL M2M SIM?
- Are there any specific settings required for BSNL M2M SIMs?
- Could this be due to SIM authentication or network rejection?
- Is there a way to disable the auto-reset behavior when the module cannot register?