[SOLVED] External applications

[sbhanot030]

My question is that many MCU have a built in 12 bit DAC and an ADC, If for a particular project I need to go to 16 bit resolution which I know might be a little excessive. An external DAC and an ADC may be required to fulfill the requirements. Is there any MCU which might have a 16 bit DAC and an ADC preferably to avoid external connections and how can I transmit data serially as a digital signal for the external DAC in STM32 since the whole process is a bit new to me in STM32CUBEIDE and STM32CUBEMX. I need a rough idea as t how I can proceed. Also I am using it in low current applications, more resolutions are needed to finetune the readings.

 

[danadakk]

PSOC 5LP has a 20 bit DelSig in it. DACs however only good for 12 bit, dithered, 15KSPS.

The rest of stuff onchip, many multiple copies :

Regards, Dana.

 

[KlausST]

Hi,

there are many external ADCs and DACs available. Each comes with a datasheet.
Just look to a distributor site and check their selection tools.

External ADCs/DACs need to communicate with the microcontroller via an interface. There are different interfaces with different features. Some are serial some ar parallel, some use 2, 3, or 4 wires, some even more.

Names of serial inerfaces: SPI, I2C, I2S, ....

What interface to use depends on your needs. Mainly sampling rate (data rate), resolution, continous vs single sampling...

If you want detailed help you need to give detailed informations first.

Klaus

 

[doraemon]

Hello!

What is your data rate?
Why not using a 14 bit MCU if 16 is excessive? Not that common, but there are some, namey
MSP432. And there are also MCUs with ADPCM 16 bits ~ 24 bits converters.
And you can have 14 bit at full speed which is 2 or 5 MSPS (don't remember. It's 2 for MSP430).
And if you need a low current application, MSP series are certainly good candidates.
Now you are not talking about the data rate. Be aware that by averaging 4 samples you get 1 extra bit. And you can scale this up if you can afford delay.

Be aware that the resolution (and accuracy) will come at the expense of added care to the
circuit design.

Dora.

My question is that many MCU have a built in 12 bit DAC and an ADC, If for a particular project I need to go to 16 bit resolution which I know might be a little excessive. An external DAC and an ADC may be required to fulfill the requirements. Is there any MCU which might have a 16 bit DAC and an ADC preferably to avoid external connections and how can I transmit data serially as a digital signal for the external DAC in STM32 since the whole process is a bit new to me in STM32CUBEIDE and STM32CUBEMX. I need a rough idea as t how I can proceed. Also I am using it in low current applications, more resolutions are needed to finetune the readings.

 

[sbhanot030]

Hello!

What is your data rate?
Why not using a 14 bit MCU if 16 is excessive? Not that common, but there are some, namey
MSP432. And there are also MCUs with ADPCM 16 bits ~ 24 bits converters.
And you can have 14 bit at full speed which is 2 or 5 MSPS (don't remember. It's 2 for MSP430).
And if you need a low current application, MSP series are certainly good candidates.
Now you are not talking about the data rate. Be aware that by averaging 4 samples you get 1 extra bit. And you can scale this up if you can afford delay.

Be aware that the resolution (and accuracy) will come at the expense of added care to the
circuit design.

Dora.

Hi
I was planning to keep the extra 2 bits for noise and any potential error which may occur in the circuit. The actual low current will just be changed by the DAC. I will be controlling that DAC with the controller. The current will of order of 1 - 10 mA only. Actually what I was planning to do is to send a particular value through the controller and let the DAC hold it until I send the next value . The DAC I am using is AD5541A which is a serial input. After processing the analog data I will get the final output through an ADC to change back into digital which I will read through the controller and display it. Sampling rate does not need to be high I believe so according to my design, If there is a problem with it can you please clarify it.

--- Updated Oct 10, 2023 ---

Hi,

there are many external ADCs and DACs available. Each comes with a datasheet.
Just look to a distributor site and check their selection tools.

External ADCs/DACs need to communicate with the microcontroller via an interface. There are different interfaces with different features. Some are serial some ar parallel, some use 2, 3, or 4 wires, some even more.

Names of serial inerfaces: SPI, I2C, I2S, ....

What interface to use depends on your needs. Mainly sampling rate (data rate), resolution, continous vs single sampling...

If you want detailed help you need to give detailed informations first.

Klaus

Hi
The external DAC that I am using is AD5541A, It is a serial input 16 bit DAC. I am interfacing it using SPI. My main aim is to improve resolution as much as possible, Sampling rate I think is not required to be high since all I need the controller is to transmit 16 bit Data and the DAC has to hold it until I send new values

 

[KlausST]

Hi,

how can I transmit data serially as a digital signal for the external DAC in STM32 since the whole process is a bit new to me

If you know you are using AD5541, then there is no option in Interface. It needs to be SPI.

Sampling rate I think is not required to be high since all I need the controller is to transmit 16 bit Data and the DAC has to hold it until I send new values

Sampling rate is independent of DAC resolution (16 bit). In so far I don´t understand this statement.

"not to be high" is meaningless. Maybe you know what it means, but we don´t. There´s a good reason we work and calculate with numbers.

****
From my experience: For me "sheet of steel" was maximum a coule of millimeters in thickness... until I worked a company that built huge bridges. The even called a 300mm (about 1 ft) thick piece of steel a "sheet".

Klaus

 

[tepalia02]

You can check DSPIC33FJ128GP. It has 16-bit DAC.

 

[danadakk]

The PSOC mentioned in post #2, DelSig at 16 bits is good for 48,000 SPS.

You could use one of its onboard PWMs, 16 bits, to do DAC. Feed that to
one of the onbboard OpASmpos to buffer its output from PWM filter.

Something like this :

Regards, Dana.

 

[doraemon]

Hello!

Sampling rate does not need to be high I believe so according to my design,

That's what I call useful information. To reply with the same accuracy, I would add that
STM32 or MSP430 and probably others might be enough for your application, and are likely
to meet your sample rate conditions as long as you don't need more.

Dora.