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How would you mult 2 or more serial input sources? — Parallax Forums

How would you mult 2 or more serial input sources?

T ChapT Chap Posts: 4,249
edited 2006-09-09 05:08 in General Discussion
I am going to receive two serial signals into a circuit to be received into an SX28, one from a 433mhz receiver, one from a MAX233. The signal is one single byte from the same Source. The MAX233 is from a sheilded wire (XLR mic cable) to be used only in case of bad reception on the UHF, probalby rarely used. In the case where the cable does get used as back up, I don't want to have to rig a switch on the Receiver box to detect a 1/4" plug's presence (using a switching 1/4" jack) to cause the SX's Sio pin to only see the inserted plug, I'd rather just Receive both signals, and mult the two inside the receiver box prior to the SC.

The modified Serin.sxb code I am using seems to wait for data at a single pin designated Sio. In this case, it appears that having two waiting Sio's is not possible, in other words, I don't know how to have two pins set to receive at the same time to facilitate one pin for the 433mhz reeiver, and one for the MAX233 output. If it is possible to set two pins in receive, please correct me. I'd prefer the least amount of parts possible, but if a logic gate is req'd to OR then that would be ok. Using an OR, would the variable that would determine the phase of the two simulataneous signals be the distance from Tx to Rx? Typically 50 feet would be max.

What about just summing the signals with 10k's just like audio? The possibility of a sync issue still exists, the UHF lagging behind the wire.

Thanks for any suggestions.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2006-09-09 04:34
    It's so simple to use a 1/4" jack that includes a normally closed switch. If the plug is in the jack, the signal comes from the plug. If the plug is not in the jack, the signal comes from the receiver. Why complicate things?
  • T ChapT Chap Posts: 4,249
    edited 2006-09-09 04:43
    Actually, I was just thinking that if the reception is bad or faulty, I'd want to override the UHF anyway.

    Good point Mike.
  • Mike GreenMike Green Posts: 23,101
    edited 2006-09-09 04:54
    I forgot to mention that you take the receiver logic level output, run it through one of the logic level to RS-232 converters and connect that to the 1/4" normally closed jack terminal. The tip terminal of the jack goes to the RS-232 to logic level converter and the output of that goes to the SX pin. The MAX233 has two of each kind of converter.
  • T ChapT Chap Posts: 4,249
    edited 2006-09-09 05:08
    I like it. Thanks Mike!


    http://www.allelectronics.com/cgi-bin/item/PHJ-8/190200/1_4%22#34;_PHONE_JACK,_SPECIAL_.html
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