Developing for Cellular Networks

Transcription

1 Developing for Cellular Networks Amanda Ervin Radical Networks Conference Brooklyn, NY 11/4-6 amandaervin.com

2 About Me Artist/Developer/Maker Wearable Devices/ Second Skins for humans This project was originally conceived as a wearable cell phone, something that would tell fictional stories about my daily experiences in a parallel world. My work in wearables often comes back to practical solutions like wearable switches for sousveillance and protest, solutions for people who can t communicate via typical senses, and allowing long distance communication for remote communication in deserts.

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7 Workshop PreRequisites Experience with embedded hardware and single board computers You write code, you love command lines Interest in Alternative Interface Design

8 Goals Next big smartphone hardware Anti-commercial networks Magic Black Box Destroyers Interface Redesigners and Wheel Re-Inventors Communication in Remote Places

9 Workshop Outline Look at Fona hardware Setup Sim Cards Connect Fona to Arduino serial communication AT commands Interface discussion and testing Lua/Python

10 Hardware Sim5320a on a Fona breakout board from Adafruit. SIM5320 Fona 3G

11 Sim5320 Voice, Text, Data, HSDPA/WCDMA/GSM, GPS over 3G (not 4G) Lua as an embedded scripting language USB, UART, I2C, SPI, Keypad, FOTA GPIO pins, Sim storage Windows driver

12 Fona 3G Additional support for connecting to the sim5320a. Fona requires two battery sources, one for power, one for serial communication. Lights. (charging, on, connected to the network) rx/tx serial interface Mic and speaker

13 What is not included Bluetooth Wifi network switching rfid/nfc Camera capabilities

14 Network Options You need a SIM card to connect to a network Ask yourself Do I just want this done for today s workshop or will I use it in the future? Do I already have a cellular plan I can add a device to (might be cost effective)? If I use Ting for it s inexpensive plans, can I maintain the plan, or am I prepared to buy new SIM cards regularly?

15 Networks Ting and AT&T tested Ting, cheap, may flag your device because it is not a prepaid service. AT&T GoPhone, not terribly expensive, won t flag your device.

16 Types of Serial Communication iic - sda, scl spi (serial peripheral interface) - lots of pins. miso, mosi, sck, cs, Vio, gnd. synchronous UART - Universal Asynchronous Receiver/ Transmitter serial - rx/tx. lots of overhead, asynchronous (baud rate extra data bits at beginning and end of transmission). voltage dependent hardware TTL (transistor - transistor logic); RS232, UART Software Serial - Bit Banging.

17 Serial Communication Character Name Char Code Decim al Binary Hex Null NUL Start of Heading SOH Ctrl A Start of Text STX Ctrl B End of Text ETX Ctrl C End of Transmit EOT Ctrl D Enquiry ENQ Ctrl E Acknowledge ACK Ctrl F Bell BEL Ctrl G should understand ascii and hex character conversion, line endings and carriage returns in particular. lf=0a, cr=0d, sc=3b (not standard) external serial comm - supposedly works on windows using a connection to the breadboard, we can get direct serial communication needs two power sources (one for power, one for logic)

18 AT Command Set ATtention AT Commands, typically used in modem technologies. Sim5320 has Extensive support for a typical command set

19 About AT Commands Hayes Command Set, Modem Command Set Part of General Telephony technology Also used for developing modems (and ESP8266s!)

20 Common commands ATDnumber; (ATD + number to dial including 1 and area code in US + ; ) ATA - answer a call ATH - disconnect call AT+CSQ - get signal quality AT+CMGS/CMGSO - send text message AT+CMGREX - read message AT+CNUM=? - GET PHONE NUMBER AT+CGREG=? - get network registration status

21 How To Get In Trouble AT+SIMEI. This changes the IMEI number. This might be legally problematic- do your own due dilligence. Tethering Make sure your network allows you to share you data with other devices. Even though it looks like one device to us, it might look like more than one device to them. For example, using a raspberry pi as a tethered interface. AT+SJDR - Jamming

22 Interfaces Arduino Uno, Micro Lilypad Adafruit Flora Raspberry Pi? No interface?

23 Lua AT commands = great! But no if statements? LUA! Lua can be compiled directly on/with your fona, so you might not need that raspberry pi after all. Lua s online Builder creates elf images, which are firmware for the sim5320

24 Next Steps Slack/ GitHub - celldev.slack.com Configuring raspberry pi with fona over uart