131 lines
7 KiB
Markdown
131 lines
7 KiB
Markdown
# PPP over Serial (PPPoS) client example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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## Overview
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A general PPP application consists of two parts: PPP server which is provided by cellular modem module and PPP client which is provided by ESP32 in this example.
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Standard operating systems like Windows and Unix integrate a full PPP stack and provide a way to setup PPP connection at the same time. But how can we get access to Internet by PPP protocol in a resource constrained system? Fortunately, the PPP protocol has already been implemented in lwIP, but it doesn't supply a common way to setup a PPP connection.
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This example introduces a library focusing on sending and parsing AT commands, and also provides useful functions to set up PPP connection.
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When PPP connection has been established, the IP packet flow from application side will be transmitted to Internet by cellular module. This example shows how to act as a MQTT client after the PPPoS channel created by using [ESP-MQTT](https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/protocols/mqtt.html) APIs.
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## How to use example
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### Hardware Required
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To run this example, you need an ESP32 dev board (e.g. ESP32-WROVER Kit) or ESP32 core board (e.g. ESP32-DevKitC).
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For test purpose, you also need a cellular modem module. Here we take the [SIM800L](https://www.simcom.com/product/SIM800.html) and [BG96](https://www.quectel.com/product/bg96.htm) as an example.
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You can also try other modules as long as they embedded PPP protocol.
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**Note:** Since SIM800L only support **2G** which will **not** work in some countries. And also keep in mind that in some other countries it will stop working soon (many remaining 2G networks will be switched off in the next 2-3 years). So you should **check with your local providers for further details** if you try this example with any 2G modules.
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#### Pin Assignment
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**Note:** The following pin assignments are used by default which can be changed in menuconfig.
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| ESP32 | Cellular Modem |
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| ------ | -------------- |
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| GPIO25 | RX |
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| GPIO26 | TX |
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| GND | GND |
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| 5V | VCC |
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### Configure the project
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Open the project configuration menu (`idf.py menuconfig`). Then go into `Example Configuration` menu.
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- Choose the modem module in `Choose supported modem device(DCE)` option, currently we only support BG96 and SIM800L.
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- Set the access point name in `Set Access Point Name(APN)` option, which should depend on the operator of your SIM card.
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- Set the username and password for PPP authentication in `Set username for authentication` and `Set password for authentication` options.
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- Select `Send MSG before power off` if you want to send a short message in the end of this example, and also you need to set the phone number correctly in `Peer Phone Number(with area code)` option.
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- In `UART Configuration` menu, you need to set the GPIO numbers of UART and task specific parameters such as stack size, priority.
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**Note:** During PPP setup, we should specify the way of authentication negotiation. By default it's configured to `PAP`. You can change to others (e.g. `CHAP`) in `Component config-->LWIP-->Enable PPP support` menu.
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### Build and Flash
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Run `idf.py -p PORT flash monitor` to build and flash the project..
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.
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## Example Output
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The example will get module and operator's information after start up, and then go into PPP mode to start mqtt client operations. This example will also send a short message to someone's phone if you have enabled this feature in menuconfig.
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### BG96 Output
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```bash
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I (1276) pppos_example: Module: BG96
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I (1276) pppos_example: Operator: "CHINA MOBILE CMCC"
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I (1276) pppos_example: IMEI: 866425030121349
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I (1276) pppos_example: IMSI: 460007454185220
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I (1476) pppos_example: rssi: 27, ber: 99
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I (1676) pppos_example: Battery voltage: 3908 mV
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I (1876) pppos_example: Modem PPP Started
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I (2656) pppos_example: Modem Connect to PPP Server
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I (2656) pppos_example: ~~~~~~~~~~~~~~
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I (2656) pppos_example: IP : 10.65.71.127
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I (2656) pppos_example: Netmask : 255.255.255.255
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I (2666) pppos_example: Gateway : 10.64.64.64
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I (2666) pppos_example: Name Server1: 211.136.112.50
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I (2676) pppos_example: Name Server2: 211.136.150.66
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I (2676) pppos_example: ~~~~~~~~~~~~~~
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I (2686) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
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I (2696) pppos_example: MQTT other event id: 7
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I (3426) MQTT_CLIENT: Sending MQTT CONNECT message, type: 1, id: 0000
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I (3856) pppos_example: MQTT_EVENT_CONNECTED
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I (3856) pppos_example: sent subscribe successful, msg_id=20132
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I (4226) pppos_example: MQTT_EVENT_SUBSCRIBED, msg_id=20132
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I (4226) pppos_example: sent publish successful, msg_id=0
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I (4646) pppos_example: MQTT_EVENT_DATA
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TOPIC=/topic/esp-pppos
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DATA=esp32-pppos
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I (4696) pppos_example: Modem PPP Stopped
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I (9466) pppos_example: Send send message [Welcome to ESP32!] ok
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I (9666) pppos_example: Power down
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```
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### SIM800L Output
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```bash
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I (1276) pppos_example: Module: SIMCOM_SIM800L
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I (1276) pppos_example: Operator: "CHINA MOBILE"
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I (1276) pppos_example: IMEI: 865992039850864
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I (1276) pppos_example: IMSI: 460007454185220
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I (1476) pppos_example: rssi: 25, ber: 0
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I (1676) pppos_example: Battery voltage: 4674 mV
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I (1876) pppos_example: Modem PPP Started
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I (2806) pppos_example: Modem Connect to PPP Server
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I (2806) pppos_example: ~~~~~~~~~~~~~~
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I (2806) pppos_example: IP : 10.188.173.2
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I (2806) pppos_example: Netmask : 255.255.255.255
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I (2816) pppos_example: Gateway : 192.168.254.254
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I (2816) pppos_example: Name Server1: 211.136.112.50
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I (2826) pppos_example: Name Server2: 211.136.150.66
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I (2826) pppos_example: ~~~~~~~~~~~~~~
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I (2836) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
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I (2846) pppos_example: MQTT other event id: 7
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I (8156) MQTT_CLIENT: Sending MQTT CONNECT message, type: 1, id: 0000
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I (8826) pppos_example: MQTT_EVENT_CONNECTED
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I (8826) pppos_example: sent subscribe successful, msg_id=26237
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I (9526) pppos_example: MQTT_EVENT_SUBSCRIBED, msg_id=26237
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I (9526) pppos_example: sent publish successful, msg_id=0
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I (10326) pppos_example: MQTT_EVENT_DATA
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TOPIC=/topic/esp-pppos
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DATA=esp32-pppos
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I (10376) pppos_example: Modem PPP Stopped
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I (14526) pppos_example: Send send message [Welcome to ESP32!] ok
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I (15076) pppos_example: Power down
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```
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## Troubleshooting
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1. Why sending AT commands always failed and this example just keeping rebooting? e.g.
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```bash
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E (626) sim800: sim800_sync(293): send command failed
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E (626) sim800: sim800_init(628): sync failed
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```
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* Make sure your modem module is in command mode stably before you run this example.
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(For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you as soon as possible.)
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