voltage from the slave/interface card in the protocol docs

[Paul Chubb]

Hi,

      While the protocol docs give a very good description of the raw protocol voltages, and how to use different VCC with the described interface, it doesn't say which base voltage the serial comms uses. Tradition rs232 uses 5-15v. Many modern systems use 3.3v and switch. Others use 3.3v. I am using a Raspberry Pi which requires 3.3v.

Cheers Paul

[Dave Liquorice]

On Fri, 16 Dec 2016 16:57:47 -0800 (PST), Paul Chubb wrote:

> it doesn't say which base voltage the serial comms uses. Tradition rs232
> uses 5-15v.

No, RS232 is nominaly positive and negative 12 V, 5-15 (+/-) would be more
or less the accepted range that gives a definate 0 or 1.

> Many modern systems use 3.3v and switch. Others use 3.3v. I am using a
> Raspberry Pi which requires 3.3v.

Some where out there(*) is the circuit of a simple single transistor and few
resistors interface between the Resol bus and a Pi. The Resol bus is
nominally 0 - 8 V, unbalanced ie. Only one wire carries the serial data.

(*) Here: https://groups.google.com/d/topic/resol-vbus/3CjZffK53ig

--
Cheers
Dave.