• AVR Freaks

SPI reliability under radiosmog

Author
ull9
Starting Member
  • Total Posts : 43
  • Reward points : 0
  • Joined: 2010/11/18 11:26:31
  • Location: 0
  • Status: offline
2011/01/13 12:30:29 (permalink)
0

SPI reliability under radiosmog

Hello Forum,

In my current projekt I face SPI reliability issue. Under strong radiosmog spi telegram - 128 bytes sometimes - contains bizzare info.
reason is obvious - radiosmog.

some questions.
1. Is there a set of SPI settings (CKE/CKP) that delivers more stable connections?
2. What clk-freq should I ude. as low as possible?
3 What other hardware issue should I pay attention to?

Thanks in advance
#1

6 Replies Related Threads

    leon_heller
    Super Member
    • Total Posts : 6411
    • Reward points : 0
    • Joined: 2004/08/17 13:19:45
    • Location: St. Leonards-on-Sea, E. Sussex, UK.
    • Status: offline
    Re:SPI reliability under radiosmog 2011/01/13 13:46:30 (permalink)
    0
    You mean you are experiencing EMC issues, presumably. Shielding and good design techniques will prevent such problems.

    Leon Heller
    G1HSM

    #2
    ull9
    Starting Member
    • Total Posts : 43
    • Reward points : 0
    • Joined: 2010/11/18 11:26:31
    • Location: 0
    • Status: offline
    Re:SPI reliability under radiosmog 2011/01/13 13:56:56 (permalink)
    0
    What is good design, here in your opinion?
    Thanks
    #3
    Stefan Uhlemayr
    Super Member
    • Total Posts : 4292
    • Reward points : 0
    • Joined: 2005/05/12 12:25:46
    • Location: Germany
    • Status: offline
    Re:SPI reliability under radiosmog 2011/01/13 14:04:33 (permalink)
    0
    ull9

    ... In my current projekt I face SPI reliability issue. Under strong radiosmog spi telegram - 128 bytes sometimes - contains bizzare info. ...
    How long is the distance your spi-bus is running? And what speed you're using?

    Greetings,
    Stefan
    #4
    ull9
    Starting Member
    • Total Posts : 43
    • Reward points : 0
    • Joined: 2010/11/18 11:26:31
    • Location: 0
    • Status: offline
    Re:SPI reliability under radiosmog 2011/01/13 14:12:00 (permalink)
    0
    app 40 cm, 1 MHz, once in 10 ms, exchange buffer 128 bytes.

    currently 5-10% is lost.
    #5
    MBedder
    Circuit breaker
    • Total Posts : 6767
    • Reward points : 0
    • Joined: 2008/05/30 11:24:01
    • Location: Zelenograd, Russia
    • Status: offline
    Re:SPI reliability under radiosmog 2011/01/13 14:25:48 (permalink)
    +2 (1)
    • Select the SPI mode which samples a data bit at its center, not at any edge.
    • Make sure both master and slaves use the same SPI mode and clock polarity.
    • Place the relatively low impedance (220..470 Ohm) line termination resistor(s) at all receiving sides.
    • Place a small resistor (22..33 Ohm) and a ferrite bead in series with any of the signal lines at the output sides.
    • Make sure your PCB is properly routed and the decoupling capacitors are properly placed everywhere.
    • Avoid passing the power supply currents via the SPI common ground line at all costs.
    • If the EMI is really very strong, use the RS422/485 differential tranceivers at both sides (this doubes the number of wires).
    #6
    ull9
    Starting Member
    • Total Posts : 43
    • Reward points : 0
    • Joined: 2010/11/18 11:26:31
    • Location: 0
    • Status: offline
    Re:SPI reliability under radiosmog 2011/01/13 14:47:50 (permalink)
    0
    Thanks a lot
    #7
    Jump to:
    © 2019 APG vNext Commercial Version 4.5