There have been two versions of the dual VNH5019 motor driver shield. The revision identifier, ash02a or ash02b, can be found printed near the upper left corner of the board (below the mounting hole). While either version should generally be a drop-in replacement for the other, there are some minor differences between the two versions.
The first revision, released in October 2011, was ash02a.
This version predated the Arduino Uno R3, so it lacked pass-throughs for the four new pins present on the R3 and all newer Arduinos.
Schematic diagram for revision ash02a (87k pdf)
The second and latest revision, released in March 2014, is ash02b.
Compared to ash02a, the following changes were made:
- Pass-throughs were added for the four additional pins (SCL, SDA, IOREF, and an unused pin) on the Arduino Uno R3 and all newer Arduinos.
- The additional capacitor through-holes, the Arduino power jumper, and the upper block of pin-remapping jumpers (for Arduino pins 8-12) were moved slightly to make room for the new pass-throughs.
- Different reverse-protection MOSFETs are used. (This does not significantly change the electrical or thermal performance of the shield.)
Schematic diagram for revision ash02b (356k pdf)