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Revision as of 11:02, 22 April 2012 by Ari (talk | contribs) (part 3 of creation)
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Release status: Design

design of Harvey
CAD Models
External Link

Harvey is yet another reprap electronics / reprap controller Board. It is built around a STM32F102 Cortex M3 and uses Sanyo LV8549M Stepper Drivers, everything on one small PCB.

Beware, this has not yet been assembled and tested. If anyone wants to check the design, please do so. In #reprap I'm gnurbs, jabber mesages go to [email protected]


This Board was designed by ari, with his personal design conceptions: SMD-Parts where available, single sided, very compact single PCB. In fact it is so small, it will need a Heat spreader for the stepper driver. Ari finds SMD-parts more convenient, especially if one produces the pcb oneself - less drilling.

Logic power (+3.3V) is supplied by USB, Power (VDD) by a 5.5/2.5 mm Jack. 8-16V are allowed, the actual voltage is measured by the µC


symbol definition
Pex expansion Header
Pprog programming header


This Board features an STM32F102 microcontroller. relevant for this Board:

  • 48 MHz Cortex M3 core
  • builtin USB
  • 2 Timers with 4 PWM channels each
  • 12-bit ADC

programming header

Pprog is the programming header. You can flash the µC over USART1 when BOOT0 is asserted during reset. These plus USART1s clock are on the header

expansion header

This header is intended for future extension. It has all the unsused pins of the STM32, with several interfaces available:

  • JTAG
  • SPI
  • I2C
  • USART1
  • _maybe_ TIM2_CH2

maybe lcd, sd-slot and some buttons would be nice

PWM Channels

I just thought I connected two pairs of stepper to the same PWM channel, so I'm listing all of them here B:=TIM2_CH, C:=TIM3_CH

B3 eEn
B4 xEn
C2 yEn
C1 zEn


just updated the schematics to B1-ePWM, B2-bPWM, but this will need nontrivial updating in the layout. Maybe it will be better to instead C3-yEn, C4-zen


Stepper Drivers are Sanyo LV8549M which are pretty dumb but require no external parts. They are not much more than two H-bridges that are controlled by two pins setting the pase and one enable. They cannot do microstepping on their own, but doing this by hand should be possible. They have an enable-pin that is said to accept PWM for current setting, but the datasheet gives no details. They are wired to PWM-channels of the µC anyway.

The Board has two


  • check if all pins on the expansion Header are 5V-tolerant.
  • connect Boot0 to Pex:11
  • put a cap between nRST and GND
  • rewire {bPWM,ePWM}^{eEn,xEn} -.-

maybe +3.3, VDD and status LED would be nice.