WISP version 4.0DL hardware

This page is for people who want to understand the state of WISP version 4.0DL hardware and firmware.
Questions? - yeagerd yeagerd, - pollyp pollyp, and - alanson alanson maintain this page.


This now-deprecated hardware version of the WISP is the version 4.0 DL, also known as "the purple WISP." It used the MSP430F2274 microcontroller, and has 32KB of flash. Most of the version 4.0 WISPs have a 1.8v voltage regulator on them, and applications that don't write to flash can run at that level. Along with the base model was the data logger version of WISP 3.0. It used the MSP430F2272 with 32KB of flash, had a real time clock, and 8K of 1.8v EEPROM. It also took an optional 0.1F storage capacitor for wireless recharging.

WISP Technical Drawings

Schematics Removed - Need copyright info added - Send a message to - alanson alanson if you need it.

WISP version 4.0DL firmware

As we mentioned above, this version used the MSP430F2274 part, which had a much larger flash than in previous WISP iterations. This was great, because we didn't have all the code space constraints that we had in earlier versions. Unfortunately, it also resulted in a lot of power consumption. Query-ack performance was acceptable, but it greatly limited the WISP range in longer communications sequences, e.g, read commands.

You'll notice references to hardware version 40A. This was a version of the 4.0DL hardware that was modified to have twinned voltage supervisor outputs. Firmware labelled hw40_XXX will run on both the modified and unmodified version of the 4.0DL. Firmware labelled hw40A_XXX will run on only on modified 4.0DL hardware.

The most recent source for 4.0DL hardware is hw40A_D51.c. It supports simple hardcoded query/acks, hardcoded reads, accelerometer sampling in the id, and accelerometer sampling in the read command. It's based on the version of firmware that Dan and Richa worked on in mid 2008 that ran on WISP 4.0DLs equipped with a 3v voltage supervisor. This version has modifications that allow it to run on a modified WISP 4.0 DL that has the 1.8v voltage supervisor (in addition to the 3v version). The implementation notes for the hw40[A] family of firmware are here.

Firmware status

Note #1: This section describes the status of the last versions of each release. See the release-specific implementation notes for status of previous versions.
Note #2: We have recently switched from CVS to SVN. CVS maintains version numbers on specific files, while SVN uses revision numbers that refer to a snapshot of a collection of files. In this table, I show both the SVN revision number that includes the file (e.g. r16) and the older CVS version number (e.g. v1.1).
Fw src
RFID protocol
Range (cold start)
known issues
hw40A_D51.c - r14/v1.1
Impinj 3.0.2
98" in query-ack and query-ack-sensor; 27" in read; 30" in read-sensor
used modified wisp #4 in test; wisp #4 X-axis is broken
see the implementation notes
hw40_D51.c - r14/v1.5
Impinj 3.0.2
71" in query-ack and query-ack-sensor; 30" in read; 29" in read-sensor
used wisp #4 in test; wisp #4 X-axis is broken
see the implementation notes
hw40_D52A.c - r14/v1.2
Impinj 3.0.2
query-ack-accel sensor
tested on #4; fix for range + accel sampling lockup bug; wisp #4 X-axis is broken; DEPRECATED
see the implementation notes


See our license page for more information.

Where to get

See our getting firmware and software page for information about our SVN code repository.

Related Resources

The MSP430F2274 data sheet is here. The errata is here .

The MSP430 User Guides are here .

Real Time Clock: RV-8564-C2

External 1.8v 8k EEPROM: 24AA08

The last modification was made by - yeagerd yeagerd on Feb 13, 2009 3:57 pm