11/6/2022 0 Comments Aardvark spi programmer![]() It would be particularly handy to allow the Slave to interrupt the Master or otherwise offer some feedback ( flow control) mechanism via interrupt. But SPI offers an elegant, protocol-agnostic mechanism for streaming d ata from sensors, audio devices, A/D converters and myriad other proprietary I/O. In regular SPI, the Master exerts all the control and only communicates with a Slave when it so desires. And it’s likely both I2C and SPI will continue to evolve as component vendors consider new protocols and bus commands.Īnd then there are devices that require interrupts, a feature not covered at all by SPI’s Master-controlled Slave-Select (SS) line. T&M equipment needs to remain flexible enough to “fit” all sizes lest engineers be forced to use multiple host adapters depending upon the device-under-test (DUT). It would be ideal if the T&M equipment supported multiple voltage levels, or even programmable ones that match tomorrow’s slave devices.Īs we’ve seen so far, despite the simple nature of both SPI and I2C and their decades-long history, both buses continue to evolve (speed, voltage, protocols, proprietary features, etc.). Level shifting circuitry adds additional timing delays, can degrade signal integrity and can possibly introduce data or I/O errors due to termination impedance, phase changes and other injected unknowns. While straightforward, level shifting adds complexity to what should be a simple debug and test environment. If the target (slave) device operates at 3.3VDC I/O, but the T&M host adapter works at 5VDC, it’s up to the test engineer to create a level- shifter board that converts signals to the appropriate levels. The trouble is that not all SPI or I2C T&M equipment handles masters or slaves of all voltages. For example, Intel’s proposed eSPI goes down to 1.8VDC some devices accept voltages as low as 0.9VDC. This latter issue-voltage-is partially a function of design flexibility and partly due to the digital evolution from 5VDC TTL down to 3.3VDC and lower. ![]() Their simplicity has made them popular, but the lack of rigorous standards and interoperability certification has left device manufacturers plenty of leeway to create their own protocol variations and voltage levels. In 2012, Version 4 added 5 MHz Ultra Fast-mode (UFm) for new USDA and USCL lines, using push-pull logic without pull-up resistors and added assigned manufacturer ID table.Īlthough now a part of the I2C specification maintained by NXP (which bought the original Philips I2C product line), not all I2C host adapters and T&M equipment support FM+, UFm, or Hs and may be limited to slower (called “standard”) I2C speeds.Īs previously mentioned, SPI and I2C are mature technologies that have found their way into countless Master and Slave devices.In 2007, Version 3 added 1 MHz Fast-mode plus (Fm+), and a device ID mechanism.In 1998, Version 2 added 3.4 MHz High-speed mode (Hs) with power-saving requirements for electric voltage and current. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |