A Harp core for the ATxmega family of microcontrollers that implements the Harp standard to serve as the basis of Harp device firmware.
The core is distributed as a static library, built for each supported microcontroller, that the firmware of each Harp device links against. It provides the common functionality that every device needs. Specifically, it:
- Handles the serial communication with the Controller, including the transmit and receive buffers
- Parses requests from the Controller and sends replies and events following the Harp Binary Protocol
- Implements the core registers and device operation defined in Device Registers and Operation, and routes requests for application registers to the device firmware
- Manages the timestamp and synchronizes it to the Harp Synchronization Clock
- Initializes and handles the microcontroller clock
The clock generator build of the core instead transmits the Harp Synchronization Clock itself, with every byte timed to the device clock.
The source code of the Harp library for the ATxmega is in the firmware folder, and the source of its documentation is in the docs folder.
ATxmega is a family of microcontrollers originally developed by Atmel and now provided by Microchip. The code is developed and built with Microchip Studio.
- Install Microchip Studio 7.0.2594, formerly Atmel Studio 7, which includes version 3.6.2.1778 of the AVR 8-bit Toolchain.
- Open the solution file core.atxmega.atsln.
- To compile, use the command Build > Rebuild Solution, or the shortcut Ctrl+Alt+F7.
- The output libraries, which are the files with extension .a, can be found in the folder firmware/bin.
Harp devices use two packages, with 44 and 100 pins. Besides more GPIOs, the main advantage of the 100-pin package is that it offers more timers.
Note: A good 32 MHz clock source is recommended, such as the MEMS oscillator DSC1001CI5-032.0000T from Microchip, which can be found on Mouser or Digi-Key.
| Signal | ATxmega32A4U | ATxmega64A4U | ATxmega128A1U | ATxmega128A4U | ATxmega16A4U, clock generator |
|---|---|---|---|---|---|
| Main Serial: CTS | PE0 | PE0 | PJ6 | PE0 | PE0 |
| Main Serial: RTS | PE1 | PE1 | PK0 | PE1 | PE1 |
| Main Serial: RX | PE2 | PE2 | PF2 | PE2 | PE2 |
| Main Serial: TX | PE3 | PE3 | PF3 | PE3 | PE3 |
| Sync Clock: RX | PC2 | PD6 | PC6 | PC2 | Not used |
| Sync Clock: TX | Not used | Not used | Not used | Not used | PD7 |
| State LED | PR0 | PD5 | PA6 | PR0 | PD5 |
| Auxiliary Serial: RX | Not used | Not used | Not used | PD2 | Not used |
| Auxiliary Serial: TX | Not used | Not used | Not used | PD3 | Not used |
| Transmit Buffer | 2048 bytes | 2048 bytes | 5120 bytes | 5120 bytes | 512 bytes |
| Library to Use | libATxmega32A4U | libATxmega64A4U | libATxmega128A1U | libATxmega128A4U | libATxmega16A4U_ClockSync |
Each library file name ends with the core version, for example libATxmega128A4U-1.15.a. The ATxmega16A4U library is the clock generator build of the core, used by the Clock Synchronizer and the Timestamp Generator Gen3. It transmits the Harp Synchronization Clock for other devices to receive, so it uses the TX line instead of the RX line.
The source code is released under the MIT license, found in the LICENSE file at the root of the repository.