The bldcMortar package delivers a standalone BLDC motor driver with Bluetooth Low Energy communication. It is aimed for hobbyist and educational usage.
bldcMortar-drive is a firmware for the bldcMortar-hardware board. This nrf52840 SoC-based board includes two DRV10983 BLDC drivers, a GPS module, two quadrature encoder inputs.
- nRF Connect SDK 2.x (tested with NCS 2.4.0)
- (optional) Visual Studio Code
- The custom bldc-Mortar board
or
-
a nRF52840-based board plus TI DRV10983 driver boards, for example nRF52840 Dongle and MIKROE BRUSHLESS 3 CLICK board should work
-
additionally a SWD programmer, a nRF52840 DK board can be used for this purpose. Not needed if a board with bootloader (eg. nRF52840 Dongle) is used.
Follow the detailed Nordic Semiconductor documentation for building and programming.
Use the mortar_board2.dts devicetree file for creating a build configuration.
| nRF52840 DK P20 header | bldcMortar-drive |
|---|---|
| VDD nRF | 3 (only if powered from DK!) |
| VDD nRF | disconnected (external power supply) |
| SWD IO | IO |
| SWD CLK | CK |
| GND | G |
| RESET | RES (disconnected for standalone boot ) |
| VDD->SWD SEL (selects the programmer target) | |
| UART TX->external 3V UART (logging tool) |
bldcMortar-drive exposes:
- 6d84a3d2-9a17-49bc-92f7-3bcc72de2137 Primary Service
- 6d84a3d2-9a17-49bc-92f7-3bcc72de2138 Characteristic, for sending commands and reading data in 8-byte messages
- 6d84a3d2-9a17-49bc-92f7-3bcc72de2139 Characteristic, for encoder 0 value, int64_t
- 6d84a3d2-9a17-49bc-92f7-3bcc72de2140 Characteristic, for encoder 1 value, int64_t
The firmware sends data to the host using notifications.
The 8-byte command (host-to-drive):
- 3 bytes as the command identifier (eg. "WRG" - "write registry")
- 1 byte as the drive id (eg. 0x01, drive 1, the second drive on the board)
- 4 bytes as the command value
Use the bldcMortar-tools to connect and drive motors. Read Texas Instruments DRV10983 datasheet and DRV10983-Q1 Tuning Guide to understand available options.
Notice logging text field in the bldcMortar-tools. It shows sent commands as:
Send command: (SPF) 53 50 46 01 ff 01 00 00
The first 3 bytes 53 50 46 are the command identifier, in this case "SPF" - speed forward. 4th byte is the drive id, 0x01, the second drive. Next two 0xFF, 0x01 equals requested speed value (511, little endian). After getting the command the nRF52840 SoC writes 0x81 (0x01 | 0x80 override bit) to DRV10983 SpeeCtrl2 (0x01) registry and 0xFF to SpeeCtrl1 (0x00) registry.
Command can be sent without using the bldcMortar-tools. Example of using bluetoothctl for sending the speed command from example above:
$ bluetoothctl
Agent registered
[bluetooth]# scan on
Discovery started
[NEW] Device 6D:8D:AE:D6:67:76 Mortar drive
[bluetooth]# scan off
[bluetooth]# connect 6D:8D:AE:D6:67:76
[Mortar drive]# menu gatt
[Mortar drive]# select-attribute 6d84a3d2-9a17-49bc-92f7-3bcc72de2138
[Mortar drive:/service0010/char0011]# write "0x53 0x50 0x46 0x01 0xFF 0x01 0x00 0x00"
By default bldcMortar-drive load registry values from the nRF52840 flash, if available. An user can save current DRV10983 registers to the flash using bldcMortar_tools or writing the "WFL" command, for drive 0 and 1 respectively:
[Mortar drive:/service0010/char0011]# write "0x57 0x46 0x4c 0x00 0x00 0x00 0x00 0x00"
[Mortar drive:/service0010/char0011]# write "0x57 0x46 0x4c 0x01 0x00 0x00 0x00 0x00"
Additionally, in the bldc_driver.c there are two constants defined:
#define DEF_MPR 0x5D //motor phase resistance
#define DEF_BEMF 0x2E //BEMF constant
bldcMortar-drive loads them before reading flash, so they are overwritten if the flash is not empty. You may like to adjust them to your motor parameters.
Check LICENSE for details.