Raf,
Get a 7i76e and you are done.
Don't scratch your head and touch sensitive components.
What you have said is technically and correct and in all the books,it's
even what the teach in tertiary educations when you're working towards
your certs. it's not exactly what I've seen in the field. That's was
day in and day out repair EFTPOS terminals, mainboards of pokies and
other sundry products by a certain large supplier of EFTPOS equipment.
Even with the latest exercise equipment with all the bells & whistles
the biggest issues are failure of output drivers due to lack of
mechanical maintenance by owners.
Not that I'm advocating working with electronic equipment in a vinyl one
piece jump suit with balloons attached.
I'm not too sure of the certification status of the RPi for industrial
use. Where as there is a variant of the BBB that is.
On 17/3/20 5:44 pm, Rafael Skodlar wrote:
Hi Peter,
On 2020-03-15 20:19, Peter C. Wallace wrote:
On Sun, 15 Mar 2020, Rafael Skodlar wrote:
"... The outputs are push pull CMOS that will drive to the output
supply rail of 3.3V. This is sufficient for TTL compatibility but
may cause problems with some types of loads. For example when
driving an LED that has its anode connected to 5V, in such
devices as
OPTO isolators and I/O module rack SSRs, the 3.3V high
level may not completely turn the LED off"
You left off a bit of the manual text:
"To avoid this problem, either drive loads that are ground
referred, Use 3.3V as the VCC for VCC referred loads, or use open
drain mode."
Peter Wallace
Mesa Electronics
I did see that but did not want to repeat too much here. It would be
nice to have a block diagram though. I prefer diagrams over long
descriptions. If nothing else, it's easier for international users to
see how to connect that board to PC, SBCs, or RPi, etc. than reading a
description in another language.
What I'm concerned about is that noise on power and some other lines
can be bigger than 3.3V which can result in totally unexpected side
effects.
Scratch your head on a dry hot day and you can generate more than 3V
of static electricity that can kill LVD chip if you touch it.
I would rather see a board that's designed for 5V and above. 6, 9, 12V
IO for driving relays, motor drivers, or other things. That would be
more robust than adding yet another board just to convert voltages
especially if IO pinouts are not standard.
Thanks for responding,
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