As defined in the project roadmap, in the first stage some technology will be developed in parallel to the definition of interfaces and protocols.
To do that it is necessary to choose a powerful yet flexible evaluation board that allowed developing and testing different devices (vehicle controller, discrete actuator,...)
Texas Instruments has recently launched a new SOC (System On Chip) called CC2652R with interesting features:
- Supports wireless communications based on the protocol 802.15.4 (as Bluetooth Low Energy, Zigbee, Thread or raw 802.15.4)
- Supports wired communications as RS-232, I2C or SPI
- Supports a wide range of analog and digital IOs and sensors (as, for instance, PWM outputs)
- Allows programming from a solid, free, environment (Code Composer Studio, or CCS) in C/C++ over real time operating systems (both Texas Instruments RTOS or FreeRTOS)
- It has a small form factor (VQFN) and contained price (around 3$)
In order to "play" with this little wonder, Texas Instruments has launched too an evaluation board called Simplelink CC26x2R Launchpad (shown in the photo) that allows an optimal integration between the CC2652R MCU and the programming environment (Code Composer Studio) thanks to its included JTAG interface. As can be seen, the evaluation board allows access to most of the MCU IOs, specifically the mapping of these IOS is defined in this table:
| GPIO Id | Pin | Type | Description | CC26x2 Launchpad mapping | Launchpad usage | User usage |
| DIO_0 | 5 | Digital | Sensor controller | DIO0 | - | DIO |
| DIO_1 | 6 | Digital | Sensor controller | DIO1_RFSW | ? | ? |
| DIO_2 | 7 | Digital | Sensor controller | UART(0)_RX | UART | - |
| DIO_3 | 8 | Digital | Sensor controller | UART(0)_TX | UART | - |
| DIO_4 | 9 | Digital | Sensor controller | I2C_SCL | I2C interface | - |
| DIO_5 | 10 | Digital | Sensor controller, high drive | I2C_SDA | I2C interface | - |
| DIO_6 | 11 | Digital | Sensor controller, high drive | PIN_RLED, PWMPIN0 | Launchpad red led, PWM0 | DIO high drive (removing Launchpad led jumpers) |
| DIO_7 | 12 | Digital | Sensor controller, high drive | PIN_GLED, PWMPIN1 | Launchpad green led, PWM1 | DIO high drive (removing Launchpad led jumpers) |
| DIO_8 | 14 | Digital | SPI0_MISO | SPI | - | |
| DIO_9 | 15 | Digital | SPI0_MOSI | SPI | - | |
| DIO_10 | 16 | Digital | SPI0_CLK | SPI | - | |
| DIO_11 | 17 | Digital | - | Not used / Not documented | ? | |
| DIO_12 | 18 | Digital | DIO12, LCD_EXTCOMIN | Sharp LCD boosterPack | - | |
| DIO_13 | 19 | Digital | PIN_BTN1 | Launchpad button 1 | - | |
| DIO_14 | 20 | Digital | PIN_BTN2 | Launchpad button 2 | - | |
| DIO_15 | 21 | Digital | DIO15 | - | DIO | |
| DIO_16 | 26 | Digital | JTAG_TDO, high drive | DIO16_TDO | - | DIO high drive |
| DIO_17 | 27 | Digital | JTAG_TDI, high drive | DIO17_TDI | - | DIO high drive |
| DIO_18 | 28 | Digital | UART(0)_RTS | JTAG UART | UART (removing JTAG Rx/Tx jumpers) | |
| DIO_19 | 29 | Digital | UART(0)_CTS | JTAG UART | UART (removing JTAG Rx/Tx jumpers) | |
| DIO_20 | 30 | Digital | SPI_FLASH_CS | SPI | - | |
| DIO_21 | 31 | Digital | DIO_21 | - | DIO | |
| DIO_22 | 32 | Digital | DIO_22, LCD_ENABLE | Sharp CLD boosterPack | - | |
| DIO_23 | 36 | Digital/Analog | Sensor controller, analog | DIO23_Analog, LCD_POWER | Sharp CLD boosterPack | - |
| DIO_24 | 37 | Digital/Analog | Sensor controller, analog | DIO24_Analog, LCD_CS | Sharp CLD boosterPack | - |
| DIO_25 | 38 | Digital/Analog | Sensor controller, analog | DIO25_Analog | - | Analog |
| DIO_26 | 39 | Digital/Analog | Sensor controller, analog | DIO26_Analog | - | Analog |
| DIO_27 | 40 | Digital/Analog | Sensor controller, analog | DIO27_Analog | - | Analog |
| DIO_28 | 41 | Digital/Analog | Sensor controller, analog | DIO28_Analog | - | Analog |
| DIO_29 | 42 | Digital/Analog | Sensor controller, analog | DIO29_Analog | - | Analog |
| DIO_30 | 43 | Digital/Analog | Sensor controller, analog | DIO30_Analog | - | Analog |
The evaluation board pricing is around 40$ and, together with the fantastic CC26X2 Software Development Kit (available for Windows, Linux and MacOS) and Texas Instrument online developer tools allows start developing code in a record time.
This evaluation board together with all the defined software is chosen as technological resource for developing the LItems on the Elbert project
Some detailed photos of the evaluation board can be seen below:
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| General evaluation board view, with CC2652R MCU on first plane |
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| Detail of the CC2652R MCU, its small size can be appreciated by comparing it with the left jumpers |
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| Detail of the CC2652R MCU. At right and left the pins giving access to the MCU IOs can be seen |
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| JTAG interface, on first plane the microUSB connector and reset button. The CC2652R MCU can be fully isolated from the onboard JTAG by removing all the jumpers on the photo, allowing both using external JTAG or using the onboard JTAG with other MCUs |
