Using scopes to paint rich pictures—of I2C and SPI buses, that is |

Using scopes to paint rich pictures—of I2C and SPI buses, that is:

Building on my last post on decoding I2 C messages, this post shows how you can combine analog traces, bus traces, and digital traces to paint a rich picture of system performance, and speed up debug in the process. The example below shows the signal interactions in a lithium-ion battery charging system. To avoid overcharging or otherwise damaging lithium-ion batteries, it’s necessary to carefully monitor temperature and charge current. In this particular design, the protection electronics communicate with the charging controller through an I2 C bus. The scope is an MSO (mixed-signal oscilloscope), and we’re using both analog and digital input channels. The goal is to understand the response times and stability of the system under various temperatures and battery states. The top trace labeled TEMPERATURE shows the analog temperature reading at the battery. The next two ana...

Full article: http://www.edn.com/electronics-blogs/scope-guru-on-signal...