Parallax has worked with the Melexis 90217 sensor in applications including CNC milling machine spindle speed measurement and feedback on motor RPM. With the CNC milling machine it reliably measured the top spindle speed of 7,500 RPM. This is a cost-effective and highly functional hall-effect sensor. The Melexis 90217 is designed to be used with a bias magnet (#605-00006) south facing the back (non-marked) side of the IC. With a single Hall plate, this sensor is immune to common rotary alignment problems.

This sensor has the following features:

• Short circuit protection
• Rotary position gear tooth sensing ability
• On-chip 10 bit A/D converter
• Self-adjusting magnetic range
• High speed operation
• No chopper delay
• Zero speed detection
• No rotary orientation concerns

Using the Melexis 90217 with a BASIC Stamp requires the use of the COUNT command for a specified duration, as shown in this example:

COUNT SpeedIn, 1000, Pulses
RPM = Pulses * 60

Downloads and Resources:
Melexis 90217 Datasheet (.pdf)
Melexis 90217 Knowledge Base and Application Notes (Off Site)