osd-contiki/platform/zoul/README.md

Zolertia Zoul core module
============================================

![Zolertia Zoul Module][zoul]

The Zoul is a core module developed by Zolertia to target most IoT applications,
providing a flexible and affordable module solution to integrate to most
existing products and solutions, or ease the prototyping and production of new
products in a short time.

The Zoul is based on TI's CC2538 system on chip (SoC), featuring an ARM
Cortex-M3 with 512KB flash, 32Kb RAM, double RF interface, and the following 
goodies:

* ISM 2.4-GHz IEEE 802.15.4 & Zigbee compliant.
* ISM 868-, 915-, 920-, 950-MHz ISM/SRD Band.
* AES-128/256, SHA2 Hardware Encryption Engine.
* ECC-128/256, RSA Hardware Acceleration Engine for Secure Key Exchange.
* Small form-factor of 16.78 x 30.89 mm.
* Prototype friendly, to fit on most prototyping boards (breadboard, etc.).
* Self-contained and EMI-protected module under a shield.

The Zoul will be CE/FCC certified (2016) to allow a fast integration and short time to market for new products and solutions.

Zoul pin-out
=============

![Zoul pin-out (front)][zoul-pinout-front]
![Zoul pin-out (back)][zoul-pinout-back]

Port Features
=============
The Zoul has the following key features:

 * Deep Sleep support with RAM retention for ultra-low energy consumption.
 * Native USB support (CDC-ACM). SLIP over UART for border routers is no longer a bottleneck.
 * DMA transfers for increased performance (RAM to/from RF, RAM to/from USB).

In terms of hardware support, the following drivers have been implemented for the Zoul-based platforms:

  * CC2538 System-on-Chip:
    * Standard Cortex M3 peripherals (NVIC, SCB, SysTick)
    * Sleep Timer (underpins rtimers)
    * SysTick (underpins the platform clock and Contiki's timers infrastructure)
    * RF (2.4GHz)
    * UART
    * Watchdog (in watchdog mode)
    * USB (in CDC-ACM)
    * uDMA Controller (RAM to/from USB and RAM to/from RF)
    * Random number generator
    * Low Power Modes
    * General-Purpose Timers. NB: GPT0 is in use by the platform code, the remaining GPTs are available for application development.
    * ADC
    * Cryptoprocessor (AES-ECB/CBC/CTR/CBC-MAC/GCM/CCM-128/192/256, SHA-256)
    * Public Key Accelerator (ECDH, ECDSA)
    * Flash-based port of Coffee
    * PWM
    * LEDs
    * Buttons
    * Built-in core temperature and battery sensor.
  * CC1200 sub-1GHz radio interface.
  * Real Time Clock Calendar (on the RE-Mote platform).
  * SD

There is a Zoul powering the RE-Mote and Firefly platforms, check out its specific README files for more information about on-board features.

Requirements
============
To start using Contiki, the following is required:

 * A zoul-based board (RE-Mote, firefly)
 * A toolchain to compile Contiki for the CC2538.
 * Drivers so that your OS can communicate with your hardware.
 * Software to upload images to the CC2538.

Install a Toolchain
-------------------
The toolchain used to build contiki is arm-gcc, also used by other arm-based Contiki ports. If you are using Instant Contiki, you may have a version pre-installed in your system.

The platform is currently being used/tested with "GNU Tools for ARM Embedded Processors" (<https://launchpad.net/gcc-arm-embedded>). The current recommended version and the one being used by Contiki's regression tests on Travis is shown below.

    $ arm-none-eabi-gcc --version
    arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors) 5.2.1 20151202 (release) [ARM/embedded-5-branch revision 231848]
    Copyright (C) 2015 Free Software Foundation, Inc.
    This is free software; see the source for copying conditions.  There is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Drivers
-------
Depending on your Zoul flavour, there are different options.  As today the RE-Mote and Firefly platforms host a Zoul with a  CP2104 USB-to-serial converter, governed by a low-power PIC to handle resetting and flashing the Zoul over USB, without having to press any button or use external tools.

The driver is available at <https://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx>

Check the board's specific README files for more information.

For windows users, if using the USB 2.0 interface (via CDC-ACM driver), there is an available driver in this folder:

`zolertia-zoul-cdc-acm`

Software to Program the Nodes
-----------------------------
The Zoul can be programmed via the jtag interface or via the serial boot loader on the chip.

Both the RE-Mote and Firefly has a mini JTAG 10-pin male header, compatible with the `SmartRF06` development board, which can be used to flash and debug the platforms.  Alternatively one could use the `JLink` programmer with a 20-to-10 pin converter like the following: <https://www.olimex.com/Products/ARM/JTAG/ARM-JTAG-20-10/>.

The serial boot loader on the chip is exposed to the user via an USB interface.  In the not so distant past we used to press a button sequence to unlock the boot loader, but now an on-board PIC in both RE-Motes and Fireflies handles this on its own, so it will detect the BSL sequence and flash the CC2538 without user intervention.

Instructions to flash for different OS are given below.

* On Windows:
    * Nodes can be programmed with TI's ArmProgConsole or the [SmartRF Flash Programmer 2][smart-rf-flashprog]. The README should be self-explanatory. With ArmProgConsole, upload the file with a `.bin` extension. (jtag + serial)
    * Nodes can also be programmed via the serial boot loader in the cc2538. In `tools/cc2538-bsl/` you can find `cc2538-bsl.py` this is a python script that can download firmware to your node via a serial connection. If you use this option you just need to make sure you have a working version of python installed. You can read the README in the same directory for more info. (serial)

* On Linux:
    * Nodes can be programmed with TI's [UniFlash] tool. With UniFlash, use the file with `.elf` extension. (jtag + serial)
    * Nodes can also be programmed via the serial boot loader in the cc2538. No extra software needs to be installed. (serial)

* On OSX:
    * The `cc2538-bsl.py` script in `tools/cc2538-bsl/` is the only option. No extra software needs to be installed. (serial)

The file with a `.zoul` extension is a copy of the `.elf` file.

Use the Port
============
The following examples are intended to work off-the-shelf:

* Examples under `examples/zolertia/zoul`
* MQTT example `examples/cc2538dk/mqtt-demo`
* Border router: `examples/ipv6/rpl-border-router`
* Webserver: `examples/webserver-ipv6`
* CoAP example: `examples/er-rest-example/`

Build your First Examples
-------------------------
It is recommended to start with the `zoul-demo`, it is a simple example that walkthroughs the zoul features (can be compiled for both the RE-Mote and the Firefly), such as the built-in sensors, LEDs, user button operation modes (press, release, hold-press), radio (Rime broadcast).

The `Makefile.target` includes the `TARGET=` argument, predefining which is the target platform to compile for, it is automatically included at compilation.  The `BOARD=` argument is using as a glue switch to pull in specific platform files, for example the specific RE-Mote core drivers.  If no `BOARD` argument is given, it will default to `remote` and compile for the RE-Mote platform.

To generate or override an existing one, you can run:

`make TARGET=zoul savetarget`

Then you can just run `make` to compile an application, otherwise you will need to do `make TARGET=zoul`.

Alternatively you can export the following to your work environment:

`export BOARD=remote` or `export BOARD=firefly`

This will avoid having to type this argument at each compilation.

If you want to upload the compiled firmware to a node via the serial boot loader you need first to either manually enable the boot loader, or just let the Co-Processor detect the flash sequence and do it on your behalf, as simple as not pressing anything at all!

Then use `make zoul-demo.upload`. 

The `PORT` argument could be used to specify in which port the device is connected, in case we have multiple devices connected at the same time.

To generate an assembly listing of the compiled firmware, run `make zoul-demo.lst`. This may be useful for debugging or optimizing your application code. To intersperse the C source code within the assembly listing, you must instruct the compiler to include debugging information by adding `CFLAGS += -g` to the project Makefile and rebuild by running `make clean zoul-demo.lst`.

To enable printing debug output to your console, use the `make login` to get the information over the USB programming/debugging port, or alternatively use `make serialview` to also add a timestamp in each print.

Node IEEE/RIME/IPv6 Addresses
-----------------------------

Nodes will generally autoconfigure their IPv6 address based on their IEEE address. The IEEE address can be read directly from the CC2538 Info Page, or it can be hard-coded. Additionally, the user may specify a 2-byte value at build time, which will be used as the IEEE address' 2 LSBs.

To configure the IEEE address source location (Info Page or hard-coded), use the `IEEE_ADDR_CONF_HARDCODED` define in contiki-conf.h:

* 0: Info Page
* 1: Hard-coded

If `IEEE_ADDR_CONF_HARDCODED` is defined as 1, the IEEE address will take its value from the `IEEE_ADDR_CONF_ADDRESS` define. If `IEEE_ADDR_CONF_HARDCODED` is defined as 0, the IEEE address can come from either the primary or secondary location in the Info Page. To use the secondary address, define `IEEE_ADDR_CONF_USE_SECONDARY_LOCATION` as 1.

Additionally, you can override the IEEE's 2 LSBs, by using the `NODEID` make variable. The value of `NODEID` will become the value of the `IEEE_ADDR_NODE_ID` pre-processor define. If `NODEID` is not defined, `IEEE_ADDR_NODE_ID` will not get defined either. For example:

    make NODEID=0x79ab

This will result in the 2 last bytes of the IEEE address getting set to 0x79 0xAB

Note: Some early production devices do not have am IEEE address written on the Info Page. For those devices, using value 0 above will result in a Rime address of all 0xFFs. If your device is in this category, define `IEEE_ADDR_CONF_HARDCODED` to 1 and specify `NODEID` to differentiate between devices.

Low-Power Modes
---------------
The CC2538 port supports power modes for low energy consumption. The SoC will enter a low power mode as part of the main loop when there are no more events to service.

LPM support can be disabled in its entirety by setting `LPM_CONF_ENABLE` to 0 in `contiki-conf.h` or `project-conf.h`.

The Low-Power module uses a simple heuristic to determine the best power mode, depending on anticipated Deep Sleep duration and the state of various peripherals.

In a nutshell, the algorithm first answers the following questions:

* Is the RF off?
* Are all registered peripherals permitting PM1+?
* Is the Sleep Timer scheduled to fire an interrupt?

If the answer to any of the above question is "No", the SoC will enter PM0. If the answer to all questions is "Yes", the SoC will enter one of PMs 0/1/2 depending on the expected Deep Sleep duration and subject to user configuration and application requirements.

At runtime, the application may enable/disable some Power Modes by making calls to `lpm_set_max_pm()`. For example, to avoid PM2 an application could call `lpm_set_max_pm(1)`. Subsequently, to re-enable PM2 the application would call `lpm_set_max_pm(2)`.

The LPM module can be configured with a hard maximum permitted power mode.

    #define LPM_CONF_MAX_PM        N

Where N corresponds to the PM number. Supported values are 0, 1, 2. PM3 is not supported. Thus, if the value of the define is 1, the SoC will only ever enter PMs 0 or 1 but never 2 and so on.

The configuration directive `LPM_CONF_MAX_PM` sets a hard upper boundary. For instance, if `LPM_CONF_MAX_PM` is defined as 1, calls to `lpm_set_max_pm()` can only enable/disable PM1. In this scenario, PM2 can not be enabled at runtime.

When setting `LPM_CONF_MAX_PM` to 0 or 1, the entire SRAM will be available. Crucially, when value 2 is used the linker will automatically stop using the SoC's SRAM non-retention area, resulting in a total available RAM of 16MB instead of 32MB.

### LPM and Duty Cycling Driver
LPM is highly related to the operations of the Radio Duty Cycling (RDC) driver of the Contiki network stack and will work correctly with ContikiMAC and NullRDC.

* With ContikiMAC, PMs 0/1/2 are supported subject to user configuration.
* When NullRDC is in use, the radio will be always on. As a result, the algorithm discussed above will always choose PM0 and will never attempt to drop to PM1/2.

### Shutdown Mode
The RE-Mote has a built-in shutdown mode which effectively reduces the power consumption down to 150nA.  Check its specific README file for more information.

Build headless nodes
--------------------
It is possible to turn off all character I/O for nodes not connected to a PC. Doing this will entirely disable the UART as well as the USB controller, preserving energy in the long term. The define used to achieve this is (1: Quiet, 0: Normal output):

    #define CC2538_CONF_QUIET      0

Setting this define to 1 will automatically set the following to 0:

* `USB_SERIAL_CONF_ENABLE`
* `UART_CONF_ENABLE`
* `STARTUP_CONF_VERBOSE`

Code Size Optimisations
-----------------------
The build system currently uses optimization level `-Os`, which is controlled indirectly through the value of the `SMALL` make variable. This value can be overridden by example makefiles, or it can be changed directly in `platform/zoul/Makefile.zoul`.

Historically, the `-Os` flag has caused problems with some toolchains. If you are using one of the toolchains documented in this README, you should be able to use it without issues. If for whatever reason you do come across problems, try setting `SMALL=0` or replacing `-Os` with `-O2` in `cpu/cc2538/Makefile.cc2538`.

Doxygen Documentation
=====================
This port's code has been documented with doxygen. To build the documentation, navigate to `$(CONTIKI)/doc` and run `make`. This will build the entire contiki documentation and may take a while.

If you want to build this platform's documentation only and skip the remaining platforms, run this:

    make basedirs="platform/zoul core cpu/cc2538 examples/zolertia/zoul examples/cc2538dk"

Once you've built the docs, open `$(CONTIKI)/doc/html/index.html` and enjoy.

Other Versions of this Guide
============================
If you prefer this guide in other formats, use the excellent [pandoc] to convert it.

* **pdf**: `pandoc -s --toc README.md -o README.pdf`
* **html**: `pandoc -s --toc README.md -o README.html`

More Reading
============
1. [Zolertia website][zolertia-site]
2. [Zolertia Wiki page][zolertia-wiki]
3. [CC2538 System-on-Chip Solution][cc2538]
4. [CC1200 sub-1GHz RF transceiver][cc1200]
5. [Zolertia Hackster channel][hackster]
6. [IoT in five days open source and online book][IoT5days]

Maintainers
===========
The Zoul and derived platforms (as well as the Z1 mote) are maintained by Zolertia.
Main contributor: Antonio Lignan <alignan@zolertia.com>

[zolertia-site]: http://www.zolertia.io/products "Zolertia"
[zolertia-wiki]: https://github.com/Zolertia/Resources/wiki "Zolertia Wiki"
[cc1200]: http://www.ti.com/product/cc1200 "CC1200"
[smart-rf-studio]: http://www.ti.com/tool/smartrftm-studio "SmartRF Studio"
[smart-rf-flashprog]: http://www.ti.com/tool/flash-programmer "SmartRF Flash Programmer"
[cc2538]: http://www.ti.com/product/cc2538     "CC2538"
[uniflash]: http://processors.wiki.ti.com/index.php/Category:CCS_UniFlash "UniFlash"
[pandoc]: http://johnmacfarlane.net/pandoc/ "Pandoc - a universal document converter"
[hackster]: https://www.hackster.io/zolertia "Zolertia Hackster Channel"
[zoul]: images/zoul-front.png "Zolertia Zoul Module"
[zoul-pinout-front]: images/zoul-pinout-front.png "Zoul pin-out (front)"
[zoul-pinout-back]: images/zoul-pinout-back.png "Zoul pin-out (back)"
[IoT5days]: https://github.com/alignan/IPv6-WSN-book "IoT in Five days online book"