Preliminary Design

The CtrlMtr board has six functional blocks: Control, ezFET, USB, Power, Motor Control, and Expansion Header. The Control, ezFET, and USB blocks will be copied from TI's reference design for the MSP430F5529 LaunchPad board. The Motor Control will be copied from the JumpMtr02 project. Only the Expansion Header is entirely new.

LaunchPad

Control, ezFET, USB

By copying the ezFET design from the TI LaunchPad design I hope to inherit the firmware programming interface as well as the COM serial device interface to the PC.

First I need to look at the schematic and BOM from the TI's LaunchPad project, which I archived as part of the JumpMtr02 project. ({THREAD_LINK:1234}). I immediately bump into the Eagle/DipTrace hurdle. I need to first open the schematic in EagleCAD and export it to DipTrace. (See {THREAD_LINK:1256}).

The LaunchPad contains 4 functional blocks:

• MSP430F5529: This is the circuit that contains the Control microcontroller. It includes a MSP430F5529, 2 external crystals (clocks), a handful of caps and resistors, and a reset switch.
• Expansion Headers: Replaced by the CtrlMtr headers.
• ezFET: Uses another MSP430 (MSP430F5528) to translate the USB interface to the SPI-By-Wire (SBW) interface to the target device, which is the MSP430F5529. Without a programming interface the entire board becomes a single-purpose component that I need to flash before shipping. I want to be able to easily reprogram the board in the field. This circuit can be omitted later to create a cheaper, single-purpose motor controller board.
• USB Hub: Allows the CtrlMtr board to communicate with an external controlling computer. This includes the USB PHY interface and the MSP430F5528 that handles the USB logic.

I will need to copy almost everything from LaunchPad design.

I need to include a JTAG programming interface to the ezFET 5528. This will be a TagConnect header to reduce the footprint and remove any headers. (See Tag-Connect) The first generation of the design needs to include a second TagConnect interface to the 5529, just in case the ezFET fails or is eventually omitted.

Power

The power section will be new. This takes in 12VDC and splits it into 12V motor and 5V USB power rails. I will be copying from the SparkFun power converter project for this. The USB circuit takes the 5V power and regulates it down to provide the 3.3V logic power rail.

Motor Control

The stepper motor controllers will be copied from the JumpMtr02 project. I will be including the thermal layer, so the entire design will be a 4-layer board from the beginning.

External Interface

Any unused GPIO or sensor pins on the MSP430F5529 will be routed to a header that allows connection to external boards. The header will include MTRPWR (12V), 5V, 3.3V, and GND pins.