CC2650 SensorTag

Overview

The SimpleLink CC2650 SensorTag is a Texas Instruments board based on the CC2650 wireless MCU. It contains multiple sensors and provides Bluetooth and IEEE 802.15.4 connectivity.

TI SensorTag v2

Features

  • CC2650 low-power wireless MCU: Bluetooth + IEEE 802.15.4 connectivity
  • Autonomous low-power sensor controller
  • Autonomous radio controller
  • Program, debug, and serial line through “DevPack” JTAG probe’s USB port
  • Power from DevPack USB or batteries
  • 2 buttons and 2 LEDs for user interaction

Hardware

The SensorTag board provides the following hardware:

  • CC2650 SoC in RGZ (7x7mm) 48 pins format package
  • Programmable Cortex-M3 CPU, clocked at 48MHz
  • Proprietary sensor controller
    • 12-bit ADC, 200ks/s
    • 2 comparators
    • SPI + I2C digital interfaces for sensors
    • Programmable with register-based interface
  • Cortex-M0 “RF Core” radio controller
    • 4KB of dedicated SRAM
    • Single transceiver, with modem and frequency synthesizer
    • Programmable with register-based interface
  • 128KB flash
  • 20KB SRAM
  • 8KB cache
  • SPI
  • I2C
  • I2S
  • UART
  • 31 GPIOs
  • 4 32-bit timers
  • True Random Number Generator
  • Real Time Clock
  • Watchdog timer
  • 32 channels DMA controller
  • 10 sensors: ambient light, digital microphone, magnetic sensor, humidity, pressure, accelerometer, gyroscope, magnetometer, object temperature and ambient temperature

Supported features

The following SensorTag features are currently supported:

Interface Controller Driver/Component
NVIC on-chip Nested Vector Interrupt Controller
UART on-chip serial port polling
GPIO on-chip gpio
PINMUX on-chip pinmux

Connections and IOs

The SensorTag has one GPIO controller, along with a flexible pin multiplexer. In practice, the pins are routed as described in boards/arm/cc2650_sensortag/board.h; the most commonly used being:

Physical pin # Digital I/O # Signal
5 DIO_0 BUTTON_2 (right)
9 DIO_4 BUTTON_1 (left)
10 DIO_5 SDA
11 DIO_6 SCL
16 DIO_10 LED_1 (red)
21 DIO_15 LED_2 (green)
27 DIO_17 SCLK
28 DIO_18 MISO
29 DIO_19 MOSI
31 DIO_21 BUZZER
41 DIO_28 UART_RX
42 DIO_29 UART_TX

System Clock

The CC2650 clocks its Cortex-M3 CPU through a 48MHz internal oscillator by default. 2 system clocks, a high-frequency one and a low-frequency one, are available to clock the CPU and the peripherals. Available clock sources for them are:

  • 48MHz internal oscillator
  • 24MHz internal oscillator
  • 32KHz internal oscillator
  • 32.768KHz external oscillator

Programming and debugging

The ROM in the CC2650 contains a proprietary bootloader, executed before the program stored on flash. The bootloader looks at a special configuration area expected to be written at the end of flash, the CCFG (“Customer Configuration” area). A 32-bit word in this area, IMAGE_VALID_CONF, needs to be 0 in order for the bootloader to actually pass control to your program. You can find more information on the CCFG in the CC2650 reference manual, section 9.1. The current CC2650 port for Zephyr already does this by default; if you wish to check or modify the CCFG content, see soc/arm/ti_simplelink/cc2650/soc.c.

Building

You can build an application in the usual way. Here is an example for the Hello World application.

# On Linux/macOS
cd $ZEPHYR_BASE/samples/hello_world
mkdir build && cd build

# On Windows
cd %ZEPHYR_BASE%\samples\hello_world
mkdir build & cd build


# Use cmake to configure a Ninja-based build system:
cmake -GNinja -DBOARD=cc2650_sensortag ..

# Now run ninja on the generated build system:
ninja
ninja flash

Flashing

The CC2650 SensorTag can be flashed using a XDS110 JTAG device, the “DevPack”, designed to plug on it. For now, flashing with it is not supported within Zephyr. However, you can use Uniflash, a TI proprietary tool, to do the job for now.

Note

Uniflash comes with some firmware for the “DevPeck” XDS110 JTAG probe. Different versions of Uniflash may have different firmware version. Currently, the most stable version is the 3.4. You should be able to grab it here: http://processors.wiki.ti.com/index.php/CCS_UniFlash_v3.4.1_Release_Notes

To update the “DevPack”, reach the installation path of Uniflash 3.4, then to the ccs_base/common/uscif/xds110/ subdirectory. Then follow the ReadMe.txt’s instructions:

$ ./xdsdfu -m
$ ./xdsdfu -f firmware.bin -r

The green LED of the “DevPack” should blink repeatedly during the operation, then light up again upon completion.

Debugging

Debugging can be done with OpenOCD 0.10, which is supported by the Zephyr SDK since v0.9.2. A basic configuration file for the SensorTag board would be:

source [find interface/cmsis-dap.cfg]
transport select jtag
gdb_memory_map enable
gdb_flash_program enable
source [find target/cc26xx.cfg]
adapter_khz 5000

Copy this in a file named ti-sensortag.cfg, located in the scripts/board subdirectory of your local OpenOCD installation path. When you wish to launch the OpenOCD server, just type:

$ openocd -f board/ti-sensortag.cfg