Hello!
I have a very simple question that's not answered in the datasheets or anywhere (that I could find) online.
What is the max current of the DACs?
DAC Max Current?
Re: DAC Max Current?
I'm going to stick my neck out (because my electronic skills are awful) and say that there may not be a story for "current" and digital to analog conversion.
My thinking works as follows. Imagine we wish to encode a signal as a voltage value. For example the digital value of 0x00 is 0 volts and the digital value of 0xff is 1 volt. Digital values between these ranges result in corresponding voltage values between 0 and 1. Effectively we have converted a digital value into its analog equivalent. The voltage present on the single output pin thus "encodes" a digital value. The measurement of that voltage will thus tell you what the corresponding digital value was that caused the resulting analog value.
What we are not saying here is that the output pin can be the source of an electrical current used to provide a current source for any kind of load. Instead, we are saying that the analog voltage output is used as an "analog signal" value where all we need to do is sense the voltage level but NOT try and draw any current from it.
(again ... all of this is just notion on my part).
My thinking works as follows. Imagine we wish to encode a signal as a voltage value. For example the digital value of 0x00 is 0 volts and the digital value of 0xff is 1 volt. Digital values between these ranges result in corresponding voltage values between 0 and 1. Effectively we have converted a digital value into its analog equivalent. The voltage present on the single output pin thus "encodes" a digital value. The measurement of that voltage will thus tell you what the corresponding digital value was that caused the resulting analog value.
What we are not saying here is that the output pin can be the source of an electrical current used to provide a current source for any kind of load. Instead, we are saying that the analog voltage output is used as an "analog signal" value where all we need to do is sense the voltage level but NOT try and draw any current from it.
(again ... all of this is just notion on my part).
Free book on ESP32 available here: https://leanpub.com/kolban-ESP32
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Fuzzyzilla
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Re: DAC Max Current?
Maybe, but there still has to be some amperage!
I thought the DACs were just (essentially) 8 outputs (with different resistances) in parallel, meaning they'd have quite a lot of current to give! I don't know though, and even if I were right, there is absolutely no documentation on which DAC is used in the ESP32... Ugh!
I thought the DACs were just (essentially) 8 outputs (with different resistances) in parallel, meaning they'd have quite a lot of current to give! I don't know though, and even if I were right, there is absolutely no documentation on which DAC is used in the ESP32... Ugh!
Re: DAC Max Current?
ooks like this question was never answered. I'm using the DAC to feed the contrast control of the LCD and it doesn't seem to be able to drive enough current to work. Can anyone answer this?
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ESP_krzychb
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Re: DAC Max Current?
Hi nkskjames,
The output current limitations of GPIO pins are discussed in https://esp32.com/viewtopic.php?f=2&t=2027#p9549.
Essentially an external circuit connected to a pin (including the two DAC capable pins) should be set up in such a way, that it does not draw more that 12mA, or the pad driving this pin may get damaged.
The output current limitations of GPIO pins are discussed in https://esp32.com/viewtopic.php?f=2&t=2027#p9549.
Essentially an external circuit connected to a pin (including the two DAC capable pins) should be set up in such a way, that it does not draw more that 12mA, or the pad driving this pin may get damaged.
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