Embedded JTAG Solutions
If you are new to EJS, get an overview of what we call Embedded JTAG Solutions, classifying them by application type and execution speed.
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As the name suggests, Embedded Board Test techniques rely on design-embedded resources to detect and diagnose manufacturing defects. JTAG / Boundary Scan is the most widely known test technique using device-embedded resources (defined in IEEE Std 1149.1 and its offspring, such as IEEE 1149.6 and other standards).
But a typical printed circuit board assembly offers many more embedded test resources one might not recognize as such initially. For example, many processors provide access to their register map through a debug port, which enables the control of processor-embedded features and board-level circuitry via access through that debug port.
PCBAs containing FPGA can be tested by configuring that FPGA with test specific resources, effectively turning it temporarily into an embedded test controller. Custom ASICs may contain a number of additional test resources that might be accessible via the JTAG test access port (TAP) or through an embedded instrument access network following IEEE 1149.1 or IEEE 1687 specifications.
Utilizing all the embedded resources a PCBA can offer makes for a very powerful test strategy that can be taken advantage of throughout the entire product life cycle.
Embedded Board Test
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Processor-assisted test and programming
Processor-assisted test and programming with our VarioTAP technology takes advantage of processor-embedded resources that can be accessed through a debug port. That debug port may be a JTAG TAP as defined in IEEE 1149.1, or it may be some other debug interface.
Once access can be gained to those embedded resources, they can be utilized for board- and system-level test and programming applications. Such applications run at a much higher speed than what can be accomplished with boundary-scan access, allowing the detection of defects that might be missed with boundary-scan test alone.
VarioTAP is based on off-the-shelf IP libraries, making processor-assisted test and programming applications accessible for users without expert knowledge.
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FPGA-assisted test and programming
As the name implies, FPGA-assisted tests utilize instrumentation that has been temporarily loaded into the FPGA, turning it into an embedded test controller on the unit under test (UUT).
FPGAs typically have access to major parts of the digital and possibly mixed-signal circuitry on the board and therefor can be utilized to exercise such circuitry to support a wide variety of application, including voltage measurements, frequency measurements, arbitrary wave-form generation, at-speed memory test, bit-error rate test, functional interface and protiocol tests, and even stress testing.
Taking advantage of the configurability of FPGAs for board test can significantly enhance the fault coverage that would be achievable with boundary scan alone.
In-system programming (ISP) refers to the task of programming components after they are mounted on a printed circuit board assembly (PCBA), and possibly installed in a larger system assembly.
Target devices can be programmed in a variety of ways, and the chosen approach often has an impact of the programming performance. Since programming components in-system most frequently rely on design-embedded resources, we group the various techniques under the term "Embedded Programming". For example, serial EEPROM devices typically are attached to processors or FPGA devices, components that more often than not implement JTAG / Boundary-Scan capabilities. This means that the target device (the serial EEPROM) can be programmed by toggeling its programming interface (typically SPI or I2C) with Boundary-Scan access from the processor or FPGA connected to it. This approach results in a notoriously slow programming time, however. The programming performance can be improved dramatically by utilizing embedded resources provided by the processor or FPGA, respectively.
Embedded Programming
FlashFOX
The award-winning stand-alone programmer FlashFOX is designed for embedded in-system programming (ISP) of microcontrollers, flash components, and PLD/FPGA.
It can be flexibly adapted to different programming requirements. The number of programming channels is scalable, allowing for the simultaneous programming of multiple devices on one PCBA or on several PCBAs.
FlashFOX is the first production programmer to support the execution of JavaScript. With the help of a graphical user interface and program generators, the JavaScript code is generated automatically, but can then also be manually edited / expanded.
The system design consists of a compact control unit and up to eight small remote PODs. Multiple control units can be cascaded, providing for a means to support large numbers of independent programming channels for debug and communication interfaces such as JTAG, SWD, DAP, SPI, I²C, and UART. Dedicated programming drivers ensure the shortest possible programming times.
