Conversation
Add support for the SIMCom SIM800L 2G module, following the existing driver architecture (Quectel, Sequans, u-blox). Key implementation details: - GSM/GPRS only: uses +CGREG instead of +CEREG for registration - SIMCom TCP/IP stack: AT+CSTT/CIICR/CIFSR for GPRS bearer, AT+CIPSTART/CIPSEND/CIPRXGET for sockets - Manual data receive mode (AT+CIPRXGET=1) for clean AT parsing - Async DNS via AT+CDNSGIP - Multi-connection mode (up to 6 simultaneous sockets) Also extends the AT session to support prefixed terminations (e.g. "0, SEND OK") used by SIM800L in multi-connection mode.
|
|
||
| main: | ||
| // Enable the board's power management IC. | ||
| power-control := gpio.Pin --output 23 |
There was a problem hiding this comment.
It would be nice to have this happen when something connects to the network.
That would require subclassing the existing class.
Investigate.
If you find a solution, don't forget to update the README.
There was a problem hiding this comment.
Following the Olimex PoE Ethernet pattern, the power IC is now managed at the service provider level. Sim800lTCallService overrides open-network/close-network to enable/disable GPIO 23. Tested with two concurrent clients — power IC stays on while any client is connected, shuts off when the last disconnects.
done
| The SIM800L operates at **3.7-4.2V** and can draw up to **2A** during | ||
| transmission bursts. Make sure your power supply can handle this. | ||
|
|
||
| - Do **not** power the module from the ESP32's 3.3V pin. |
There was a problem hiding this comment.
More importantly: don't power it with the 5V.
| - Do **not** power the module from the ESP32's 3.3V pin. | ||
| - A LiPo battery (3.7V, 1200mAh+) or a 2A-capable DC-DC converter is recommended. | ||
| - Some boards (like the LilyGO T-Call) include a power management IC. | ||
|
|
There was a problem hiding this comment.
Also add a note that the 3.3V can't go directly to the module for the RX.
| ## Limitations | ||
|
|
||
| - 2G (GSM/GPRS) only — no LTE support. | ||
| - Maximum 6 simultaneous TCP/UDP connections. |
There was a problem hiding this comment.
How does our driver handle things when there are more connections?
There was a problem hiding this comment.
The driver throws ResourceExhaustedException when all 6 slots are in use (tested on hardware). Updated README.
done
|
|
||
| - 2G (GSM/GPRS) only — no LTE support. | ||
| - Maximum 6 simultaneous TCP/UDP connections. | ||
| - Maximum ~1460 bytes per send operation. |
There was a problem hiding this comment.
Same question: what happens if we try to send something bigger? Do we chunk correctly?
There was a problem hiding this comment.
TCP try-write_ chunks automatically (if to - from > MAX-SIZE_: to = from + MAX-SIZE_). UDP throws if over MTU. Updated README.
done
| connect_: | ||
| // On SIM800L, the connection is established after CIPSTART returns OK. | ||
| // The "<id>, CONNECT OK" notification is not a standard URC and is | ||
| // handled by the sleep in the constructor. |
There was a problem hiding this comment.
Not a fan of this. Is there no way to wait for this? We can change the 'at.toit' if necessary.
There was a problem hiding this comment.
Addressed together with the comment above.
done
| if to - from > MAX-SIZE_: to = from + MAX-SIZE_ | ||
| data = data.byte-slice from to | ||
|
|
||
| e := catch --unwind=(: it is not UnavailableException): |
There was a problem hiding this comment.
no need to assign to a local if we don't do anything with it.
| cellular_.sockets_.remove id | ||
|
|
||
| mtu -> int: | ||
| return 1500 |
There was a problem hiding this comment.
Is this related to the MAX-SIZE?
There was a problem hiding this comment.
They are related but distinct: MTU (1500) is the IP-level maximum, MAX-SIZE_ (1460) is the SIM800L per-AT-command data limit (≈ MTU minus TCP/IP headers). Added a clarifying comment.
done
| "$address.port", | ||
| ] | ||
| // Wait for CONNECT OK. | ||
| sleep --ms=3000 |
There was a problem hiding this comment.
Same as for the tcp socket. Can we monitor the TX somehow?
There was a problem hiding this comment.
Addressed together with comment on simcom.toit:94.
done
| else: | ||
| parts | ||
|
|
||
| // CCID response parser (ICCID is too large for int). |
There was a problem hiding this comment.
What does this mean?
ints in Toit are 64 bit.
There was a problem hiding this comment.
Reworded: ICCIDs are 19-20 digits. A 64-bit signed int holds up to ~9.2×10^18 (19 digits), so 20-digit ICCIDs overflow. The custom parser reads the value as a string to avoid inconsistent behavior from the default int-parsing fallback.
done
1 participant
Add support for the SIMCom SIM800L 2G module, following the existing driver architecture (Quectel, Sequans, u-blox).
Key implementation details:
Also extends the AT session to support prefixed terminations (e.g. "0, SEND OK") used by SIM800L in multi-connection mode.