serout2 using Open Inverted

[Charles Linquis]

If you connect the serial outputs of two PICs together, you should always use the OPEN mode. Use a pull-up to Vcc. 3.3K is a good choice for a value.

[Pimentel]

Thanks Charle and Steve!

I tested wiring the 2 pins of 2 PICs together with a 4K7 pul up resistor, but it did not function. Then I removed the electrical resistance and I got success!
I used ON mode (serout2 portb.0,49xxx) <=> ON9600

Thanks again

Pimentel

[Charles Linquis]

Something is strange then, because when you are using the device in the OPEN mode (if you truly are), then there is no way it will work without a resistor connected to the wire between the PICs and to Vcc. Note that the OPEN mode only makes sense on the SEND side (SEROUT).

That is, if you have PICs #1 and #2 both sending data to PIC #3, then Pic #1 and #2 should be in the OPEN mode. PIC #3 does not have to be in the OPEN mode to receive the data (but all devices must be either TRUE or INVERTED), and you must have a pull-up on the wire that connects the output of PIC#1, PIC#2 and the input of PIC#3.

[Pimentel]

Hi,

Explaining better… I have 2 PICs sending data for a radio configured for 9600, N, 8,1. When I insert a 4k7 resistor to VCC the circuit fail.
Now, as attached figure always functions!

[Bruce]

For inverted serial the TX pin should idle low, so a pull-down resistor would be
required. If you were using true mode then a pull-up resistor would be needed.

[Pimentel]

Hi Bruce,

Now I understood. I go to insert a pull down resistor then!

Thanks again

Pimentel