In-System / In-Circuit Programming (ISP): Popular Programming Trend
In-system / In-Circuit programming (ISP) is becoming a popular programming technique where a programmable device is configured after it is placed in a circuit board. Many modern programmable devices can be reprogrammed without being removed from the circuit board, thus eliminating extra handling steps required during manufacturing.
ISP is beneficial because n>ew technology trends make using serial ports, such as JTAG, essential for dramatically reducing development and production costs, speeding test development through automation and improving product quality because of increased fault coverage. While it is obvious that JTAG based testing can be used in the production phase of a product, new developments and applications of the IEEE-1149.1 standard have enabled the use of JTAG in many other product life cycle stages. JTAG technology is now applied to product design, prototype debugging and field service.
Programming Problems with Modern Devices
- Many boards include components that are assembled on both sides of the board. Most of the through-holes and traces are buried and inaccessible.
- Loss of physical access to fine pitch components (i.e. SMTs and BGAs) makes it difficult to probe the pins and distinguish between manufacturing and design problems.
- Small-size products do not have test points, making it difficult or impossible to probe suspected nodes.
- Every time a new processor or a different flash device is selected, the engineer has to learn from scratch how to program the flash memory.
- When a design includes CPLDs from different vendors, the engineer must use different in-circuit programmers to program the CPLDs.
In-Circuit (ISP) Programming Solutions
- Allows programmable electronic chips to be programmed while installed in a complete system.
- Allows engineering and manufacturing facilities to shorten the development cycle by integrating programming and testing into a single production phase.
- Reduces the possibility of damaging leads of surface mount devices and damaging devices through electrostatic discharge (ESD).
- Allows manufacturers to eliminate delays and not have to purchase preprogrammed chips from a chip vendor / distributor.
- Is feasible to apply code or design changes in the middle of a production run.
- Allows the use of the Automatic Test Equipment (ATE) to perform operations on ISP devices and integrate operations with normal production test flow.
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