Timeline for SPI Bus Termination Issue
Current License: CC BY-SA 3.0
Post Revisions
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 13, 2017 at 12:32 | history | edited | CommunityBot |
replaced http://electronics.stackexchange.com/ with https://electronics.stackexchange.com/
|
|
| Oct 15, 2015 at 22:58 | vote | accept | shraken | ||
| Apr 23, 2015 at 0:40 | comment | added | shraken | Appreciate the help Alex and Efox29. As Alex mentioned, it was the edge slew rate (100-nsec) that was the issue. The issue observed was independent of the SPI clock frequency. I ended up having to put a RC LPF on both the SCLK and MOSI lines to get it to work. I ended up using a 330R/47pF RC filter which has a -3dB of roughly 9.5 MHz. Interesting enough, it only worked when RC LPF was placed on both on both SCLK and MOSI lines. | |
| Apr 23, 2015 at 0:39 | vote | accept | shraken | ||
| Oct 15, 2015 at 22:57 | |||||
| Apr 19, 2015 at 18:00 | answer | added | Rolf Ostergaard | timeline score: 8 | |
| Apr 19, 2015 at 8:25 | comment | added | alex.forencich | And with this sort of an issue, it's the edge slew rate that's the problem, not the clock frequency. If you see the same problem independent of clock frequency, then the fast edges are the problem and need to be slowed down. | |
| Apr 19, 2015 at 8:23 | comment | added | alex.forencich | I would suggest starting with the SCK line first before adding Rs and Cs to the other lines. After all, edges only matter on the clock line, the other lines will be more tolerant of reflections. | |
| Apr 19, 2015 at 6:51 | comment | added | efox29 | How is your system with with a slower clock like 50Khz ? What is the microcontroller you are using ? | |
| Apr 19, 2015 at 6:01 | history | tweeted | twitter.com/#!/StackElectronix/status/589670104931139584 | ||
| Apr 19, 2015 at 5:59 | comment | added | shraken | Hi efox29, yes but it will be a bit dirty. My SPI master is on a SOM mounted to my daughterboard. My intention is to cut the trace for SCK and MOSI and mount a 330-ohm/47pF 0603/0805 RC for each using epoxy/glue and do something similiar on the A/D and magnetometer boards for MISO. I'll try and make the GND stub to as close as GND pad or plane I can get. Holding off on this till I hear more back but plan to try tomorrow. I don't have ability to change SPI into a daisy-chain or anything though. Wouldn't do much good anyways, boards need are at opposite ends. | |
| Apr 19, 2015 at 4:58 | comment | added | efox29 | Do you have the ability to add series resistors and change the wiring ? | |
| Apr 19, 2015 at 3:13 | history | asked | shraken | CC BY-SA 3.0 |