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ee:hydrophones:start [2018/01/28 16:30] Ryan Summers [FPGA Design] |
ee:hydrophones:start [2018/01/28 16:32] Ryan Summers [Software Design] |
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| //Note: For simplicity, the HydroZynq is programmed bare-metal. There is no operating system on the board!// | //Note: For simplicity, the HydroZynq is programmed bare-metal. There is no operating system on the board!// | ||
| - | The software design is straightforward, but the most complex of the other systems. Communication with other computers is implemented using UDP sockets provided by the lwIP (lightweight IP) library. When the CPU first boots, it loads the program off the SD card into memory. It then programs the FPGA bit stream and begins program execution after initializing most peripherals (e.g. Xilinx Ethernet). The application then initializes peripherals that were instantiated in the FPGA fabric (such as the ADC reader, the system monitor, and the SPI engine). It then configures the ADC chip and binds/connects to a variety of UDP ports for communication. | + | The software design is straightforward, but the most complex of the other systems. Communication with other computers is implemented using UDP sockets provided by the [[http://www.nongnu.org/lwip/2_0_x/index.html|lwIP (lightweight IP) library]]. When the CPU first boots, it loads the program off the SD card into memory. It then programs the FPGA bit stream and begins program execution after initializing most peripherals (e.g. Xilinx Ethernet). The application then initializes peripherals that were instantiated in the FPGA fabric (such as the ADC reader, the system monitor, and the SPI engine). It then configures the ADC chip and binds/connects to a variety of UDP ports for communication. |
| The software first attempts to sync onto the ping. Because the ping happens every two seconds, once the first ping has been found, the system can consistently find every other ping afterwards. To acquire initial synchronization, the code samples the hydrophones for 2.2 seconds. It then scans this period for the earliest start of a ping (by performing a threshold detection). It then calculates at what exact time the ping started and schedules sampling to begin at the next future ping. | The software first attempts to sync onto the ping. Because the ping happens every two seconds, once the first ping has been found, the system can consistently find every other ping afterwards. To acquire initial synchronization, the code samples the hydrophones for 2.2 seconds. It then scans this period for the earliest start of a ping (by performing a threshold detection). It then calculates at what exact time the ping started and schedules sampling to begin at the next future ping. | ||
