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RS232 decoding vs UART decoding - Rigol ds1054z seems confused (or maybe I am)
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mbratch:
I'm using the Rigol DS1054Z to decode UART output form an ESP32 mcu.

What I'm finding is that the Rigol appears to have the decoding inverted and changing polarity causes it to get confused.

The UART output of the ESP32 is a 3.3v level output and so in stead state it is "high" (3.3v) and a "1" is 0 volts and a "0" is 3.3 volts. All sounds pretty normal so far.

When I attempt to decode using the Rigol RS232 decoder, if I set the polarity match this it decodes beautifully but the hex values are inverted. So I have to manually invert all the hex values it shows me by hand (or at least in my head as I'm reading them). I tried fooling it and selecting the opposite polarity, but then it was confused and gave question marks and completely incorrect values for the decode. I suppose it was confused about start/stop bits (?).

I haven't seen any other comments on this issue, so I assume I must be doing something wrong. Does anyone have a suggestion?
langwadt:

--- Quote from: mbratch on June 02, 2024, 06:40:06 pm ---The UART output of the ESP32 is a 3.3v level output and so in stead state it is "high" (3.3v) and a "1" is 0 volts and a "0" is 3.3 volts. All sounds pretty normal so far.

--- End quote ---

that's not pretty normal, a normal uart idles high and 1 is high and 0 is low
mbratch:

--- Quote from: langwadt on June 02, 2024, 06:53:32 pm ---
--- Quote from: mbratch on June 02, 2024, 06:40:06 pm ---The UART output of the ESP32 is a 3.3v level output and so in stead state it is "high" (3.3v) and a "1" is 0 volts and a "0" is 3.3 volts. All sounds pretty normal so far.

--- End quote ---

that's not pretty normal, a normal uart idles high and 1 is high and 0 is low

--- End quote ---

Ah ok... I was having trouble finding that information. That was my misunderstanding. Thanks!

So it appears that the UART driver in the ESP32 library inverts the bits, which I'll need to dig into.
langwadt:

--- Quote from: mbratch on June 02, 2024, 07:03:58 pm ---So it appears that the UART driver in the ESP32 library inverts the bits, which I'll need to dig into.

--- End quote ---

that would be very odd
2N3055:
Inverting hex values could be about MSB/LSB (Bit order) setting.
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