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In order to have 4 detectors instead of 2 on the same pcb.
1642698534
That is clear (ST CMOS gate, such as in "logical gate"?)
Query shelved, that will be two detectors per comparator. Adding a CMOS gate, although a good idea, defeats my purpose to limit the number of comparators/gates/.. per...
Hi Klaus, thanks for your suggestion. But I prefer to keep it simple and cheap.
Microcontroller: extra cost (hardware and software), extra space on the pcb, extra maintenance headache, extra production cost, .. No please, at most an extra mosfet besides C and R.
EDIT: and drift is no issue, no...
Purpose of this design: detect light variation at low intervals (>1 second, up to minutes).
This detection circuit works independent of ambient light.
What I do need is a delay on the output, only when LDR is uncovered, ie when the voltage on the non-inverting input recovers to a high level...
That is the point: when using a controller based board without UART then RX and TX are handled by a software serial part in its program.
"..why not simply swapping bus wires..": if polarity can be handled by software, why bother?
But I guess I have to post this in a software specific forum.
Erik
I was thinking of a software solution: if at idle RX is not high then polarity of incoming bits must be inverted. Something like that?
The fact there is no hardware UART means that software parses what is incoming; so if the expected idle "high" state is not there, then inverse whatever follows..?
Is there a way to correct this in software? The controller I use (AtMega328 in "pro mini" version) does not have a UART chip, TX and RX are directly read by the controller.
EDIT: By "correct" I mean: allow for polarity inversion.
/* http://www.utrainia.com/65-arduinocmri-and-rs485
/* Arduino...
@brian: trace 3 (pink) effectively is a 2V/div signal, but the scope had inadvertently been set at x10 instead of x1 for this channel as that is the actual probe setting.
I think the issue is solved.
A and B polarity do matter here: I had disregarded this requirement.
Attached: scope screen...
Hi,
a comment by Klaus a few posts higher about the high default state of the TX and RX lines, and my yesterdays post where I noticed that default on the working breadboard is high, but not so on the PCB made me look at the polarity of A & B.
Coincidentaly on the breadboard A & B always were...
Ah ok, screenshot of .brd: see attached.
Also pictures of setup: both breadboard, and PCB, with exactly same controller and MAX485.
Also scope printscreen or RX both for breadboard (2) and PCB (3).
Sorry to read your comments:
1. I do not understand what you mean by "Eagle comments". But the board is finished to the requirements of the fab.
2. A pdf was uploaded because that is what I got from Eagle
3. Photos to verify wiring: if I confirm that my wiring is checked and double checked then...
This device acts as a slave.
Yes data arrives properly at the controller (scope screenshot in first post).
Baud rates for master and slave are synchronised (19200), comms work in breadboard "mode".
RX is idle low.
MAX485 states no resistors required in RX and TX lines.
Incoming line might need...
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