BitScope Loop Q/A Test

A quality assurance and testing system for BitScope Micro.

Manufacturing a product in high volume at low cost requires an efficient automated quality assurance process to test and verify the product functions correctly and that it meets its design specifications.

BitScope Loop is a graphical test and verification platform designed to perform Q/A testing on BitScope itself. It is a self hosted "loopback" system that allows a new BitScope straight off the production line to be used to perform its own quality assurance including connectivity tests, input compensation, signal generation, capture timing and I/O verification.

Q/A Test Plug | Self Test & Verification

One of the things that sets BitScope apart from other test & measurement products is that it is a fully programmable mixed signal test, measurement and diagnostic system. It can generate and capture analog and digital signals as well as provding switchable test vectors for a circuit under test. In short, it has all the pre-requisites to be able to test itself.

The missing element is the circuit under test.

For this BitScope Loop makes use of a loop back Test Plug.

The test plug is a mixed signal circuit that plugs into BitScope Micro to enable the use of the Diagnostic Port in loop back mode.

The test plug implements a trivial passive circuit which allows a full suite of functional tests and high frequency bandwidth compensation operations to be performed. The test plug is a deceptively simple but carefully crafted passive test circuit which implements a number of filters and delay lines.

By generating a set of analog and digital test signals and switching among a series of tests, BitScope Micro is able to perform all the Q/A tests required to confirm its correct operation. This includes testing voltages, checking for phase and timing errors and enabling the detection of common manufacture faults including open and short circuits, solder bridges and even detecting subtle impedance or component errors which affect frequency response and timing.

One simply connects the test plug and the software performs the test sequence automatically.

BitScope PiLab | Diagnostic Applications

BitScope Loop is written in Python for BitScope PiLab on Raspberry Pi.

BitScope PiLab is a programming platform that enables the creation of custom test, measurement and data acquisition applications in educational, engineering and scientific fields. It provides a simple PNG based graphical UI that requires no complicated widget libraries.

BitScope Loop comprises two PiLab Apps; Test and Verify.

Each application executes a stepped sequence of test screens which show waveform and other displays as well as representative images of the product itself. Test executes the primary tests and directs the compenstation of the inputs. It is applied when a new BitScope is first manufactured. Verify checks the compensation has been applied correctly and confirms the full Q/A process has completed after final assembly.

Requirements and Compatibility

BitScope Loop runs on Raspberry Pi and other Linux systems that support Python 2.7 and have a spare USB port. A BitScope Micro and test plug circuit is required to run successfully. A test plug can be made from this schematic.

Download BitScope Loop using the button at the top of this page.