jbaker0428 / unified-robotics-development-board Goto Github PK

Digikey only carries the 8-VDFN variant of the AOZ1036, will have to find/make the package and make a new device variant in aos.lbr.

Need to break out the DAC to a header, it's not being used directly for anything on the board.

Need to add a header for hobby PWM servos. How to supply servo-friendly voltages needs to be decided as well.

Some of the onboard sensors have some extra IO pins beyond the serial interfaces that still need to be addressed. Ensuring IO pins on the XMOS are free for these signals is top priority.

Quadrature encoder interface hasn't really been investigated yet.

Need more decoupling capacitors for the microcontrollers. The XMOS specifies one per pin -- for layout reasons with the QFN package we can keep that to one per pair.

From the STM32 manual:

• The VDD pins must be connected to VDD with external decoupling capacitors; one single Tantalum or Ceramic capacitor minimum 4.7 µF typical 10 µF) for the package + one 100 nF Ceramic capacitor for each VDD pin).
• The VDDA pin must be connected to two external decoupling capacitors (100 nF Ceramic capacitor + 1 µF Tantalum or Ceramic capacitor).
• The VREF+ pin can be connected to the VDDA external power supply. If a separate, external reference voltage is applied on VREF+, a 100 nF and a 1 µF capacitor must be connected on this pin. To compensate peak consumption on Vref, the 1 µF capacitor may be increased up to 10µF when the sampling speed is low. When ADC or DAC is used, VREF+ must remain between 1.8 V and VDDA. VREF+ can be grounded when ADC and DAC are not active; this enables the user to power down an external voltage reference.

As many of the linear regulators currently on the board as possible should be replaced with switching regulators. The separate 3.3V rails made more sense with the second XCore, which is no longer a consideration. A single switching regulator will easily be able to provide enough current for all 3.3V devices on the board.

The RST_N pin on the XMOS is currently blocked in. The XTAG trace escaping needs to be adjusted to accommodate it.