The main power entry point of the system is through the motherboard by using the two battery connectors with two 6V / 2400mAh packs put in series. The 12V is then reduced to a 5V rail through a buck converter. The daughterboard is then fed with the 5V to provide a 3.3V rail.
An extra connector allows for an NiMh charger to be connected.
Make sure to shut the circuit off while charging to avoid higher voltage on the 12V rail.
The charge rate should be of around 0.05C => 120mA here.
A switch must be connected to the corresponding port to power the board. Then, the 12V is transported to the PMODs and the buck converter through a 3A-T fuse.
Please test the circuit with a DC power supply with current limitation capabilities.
If the fuse breaks, check for any short-circuit before replacing it and power-cycling the circuit.
A green LED shows the board power status.
An I2C dual-inputs ADC converter (MCP3426A0) is present on the board to read both the battery voltage and the current consumption.
Access the data
The chip is read from the FPGA each second through dedicated I2C lines.
The information can be read from the smartphone at will by accessing the corresponding registers.
The daughterboard is mounted through an SODIMM-200 (DDR2 RAM) connector.
The board allows for multiple I/Os to be plugged following the PMOD wiring, lightly modified for the Kart, under the following form:
- 4 full connectors for direct plug (PMODs 5 to 8)
- 3 full connector for flat-cables
- 1 half connector for flat-cable
PMOD8 pins 6 to 8 cannot be used with the AGLN250. In such case, use the connector on one row (the upper one).
The pins are described on the board itself and correspond to the following:
Various sensors can be wired as seen here.
A small button allows the user to reset the FPGA from the motherboard.
Both Tx from the FPGA and the BLE module can be sniffed by wiring a dedicated UART-USB chip to the provided headers.
The Bluetooth - USB dongle can be inserted in its dedicated socket to control the Kart with a smartphone, or easily removed to be plugged in a PC directly.
One can emulate the BLE module with the help of a custom serial interpreter by simply plugging the daughterboard in a PC through the USB-C. The communication is merged between both the PC and the BLE module.