Embedded System Architecture Automatic Test Equipment Computerized Jtag Programming Tutorial: Designers using fine-pitch packages in embedded applications are discovering new On-Board Programming methods for these devices. This article shares information about two different On-Board Programming methods: programming with Automatic Test Equipment and programming using the IEEE 1149.1 JTAG test access port.

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by Peter T. Larsen. Intel Corp.

Vendors such as Intel recognize that consumer buying trends are driving the creation of smaller flash memory package sizes—significantly smaller even than the popular TSOP. For example, the flash memory micro-BGA package is a true CSP (chip size package) that gives system design engineers the smallest available flash memory footprint. In addition, micro-BGAs are supported with today's installed surface mount tool capability, so that SMT lines featuring such equipment as pick-and-place and IR reflow can handle the devices with minimal-to-no cost or processor changes. Finally, the package design permits trace routing underneath the package using standard PCB design rules, which often results in a small footprint than a chip-on-board solution.

Advantages and limitations
Manufacturers incorporate on-board programming (OBP) to quickly and efficiently program components and to gain cost savings associated with this less expensive process. Nevertheless, any programming solution, including OBP, has advantages and limitations that must be considered in relation to the application.

For example, OBP, by definition, eliminates off-line programming. The software is written while it is mounted on a PCB. OBP also reduces manual handling of components, eliminates individual device-labeling, and enables use of economical tape-and-reel shipping media for flash memory components. The advantage here is that product assembly is quicker from tape-and-reel than from trays because, with the former, a mechanical search for a component is not required. In high-volume manufacturing, every second saved affects profit margins favorably. Last, with OBP neither inventory storage nore additional handling equipment for fin-pitch packages are required. On the other hand, in some cases additional hardware for OBP is required to avoid bus contention. Designers may need to use connectors to link PCB applications to OBP equipment.

Throughput (beat-rate) will decrease by the time required for programming. And PCBs with limited space may not accommodate test land pads. (In this case, alternative OBP methods such as using the JTAG access port can be used.)

Device requirements to perform OBP
To perform on-board programming, the target device must be receptive even if other devices are connected to its pins. Compatible devices include flash memories, EEPROMS, EEPROM-cell–based PLDs for in-circuit programming, EEPROM-cell FPGAs for in-circuit programming, and microcontrollers containing internal EEPROM.

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© 2005 Intel Corp.