Multiprocessor communication using a USART

[Danny Leach]

Posted on November 27, 2017 at 23:10

Can someone please direct me to a comprehensive explanation of Multiprocessor communication using a USART.  I have reviewed paragraph 31.5.7 of RM0385 and still have questions.

Thank You 

[T J]

Posted on November 28, 2017 at 00:38

In the old days, sometime after they invented wires.

They made a simple diode  and that lead to a multi-drop technology, originally called DTL logic

that is used in 100% of all electronic equipment ever.

simplistically, with a voltage and pull up resistor connected to 1000 diodes, through any one diode, you can pull to ground.

simplistically, any processor Tx Pin can pull a diode circuit and every other processor can listen. everyprocessor is listening to a single channel ( a wire with diodes)

that is multidrop communications

RS232 is a point to point technology not suitable for multidrop at a distance.(although in half duplex it can be done with a diode as discussed upto a Meter)

but usual multidrop comms is usually done with these,

RS485 is almost identical to CanBus on the wire, both use the multidrop diode method somehow.

I'd recommend: CanBus is an extremely fast, anti-collision system that seems bulletproof under 1 km.

Distance and Bandwidth requirements determine the cable/radio requirements

LoRa radio seems the next level for a few kms. (upto 5 km line of sight.  refer to Clive's work

https://community.st.com/community/stm32-community/blog/2017/04/05/lora-discovery-kit

 )

[Danny Leach]

Posted on November 28, 2017 at 17:00

What I was look for was documentation outlining setup of the STM32 USART in support of the two wire multiprocessor functionality.   Not condescending rhetoric and redirection to unrelated off the shelf stuff . 

But Thanks anyway!!