Figuring out pinout schematic of an ATtiny chip

I want to build my own development board for a project I am working on using an ATtiny441. However I can't figure out the pinout schematics as to which pins should serve as analog and which ones should serve as digital. From the schematic shown here, beside the VCC and GND all the other pins are labeled ADC which is the source of my confusion. Any help would be very much appreciated.

Any pin can be used as digital input and digital output and as analog input. Pin marked as PWM can be used as analog output.

The image on this page details the available functions for each pin:

https://github.com/SpenceKonde/ATTinyCore/blob/master/avr/extras/ATtiny_x41.md

alesam: Pin marked as PWM can be used as analog output.

They can be used as PWM output, not as analog output (the analogWrite() function is terribly named).

For an analog output you need a DAC, which ATtinies don't have.

wvmarle: They can be used as PWM output, not as analog output (the analogWrite() function is terribly named).

For an analog output you need a DAC, which ATtinies don't have.

Conversion from Digital to Analog can be achieved by many ways. Pulse Width Modulation is one of them.Power delivered by PWM signal is directly proportional to value of analogWrite() argument.

PWM output is a block wave output, it's not a proper analog output. The two are really very different things, don't mix them up. That the command is called analogWrite() doesn't make it so. It's a confusing misnomer.

Don't believe me? Connect it to an analog input and see what garbage you get out of it when you do a succession of analogRead() calls. You'll get a rather random string of 0 and 1023 values.

Of course you can convert a PWM signal into an analog voltage signal using a low pass filter, preferably in conjunction with a buffer (unity gain OpAmp).

1. Pin numbers in Black Ink are the physical pins of the IC. Pin numbers with RED Ink are the DPin (digital pin) numbers given by the Arduino IDE. When we say Pin-7, we will refer to the physical pin of the IC and not to DPin of IDE.

2. There are more than one signals attached with a pin. For example: Pin-7 is attched with the following different 5 signals:
(ADC6/PWM/SDA/MOSI)PA6

(1) 4 signals are within a pair of parentheses -- (ADC6/PWM/SDA/MOSI). These are the alternate functions of Pin-7 whcih can (only one function at a time) only be invoked by 'initialization'.

ADC6: Pin-7 will acquire external analog signal for Ch-6 of the internal analog-to-digital converter.
PWM: Pin-7 will output Pulse Width Modulated Signal.
SDA: Pin-7 will work as the bi-directional SDA (Serial Data Line) for the I2C Bus.
MOSI: Pin-7 will work as the 'Master Out Slave In' line of the SPI Port.

(2) One signal named PA6 is lying outside the pair of parentheses. This is the primary function of Pin-7 by default. The pin will work as digital IO (input/output) line to exchange 1-bit data with external devices.

3. Similar interpretations could be made for the signals of the other pins of the MCU.

wvmarle: PWM output is a block wave output, it's not a proper analog output.

Hmm. Define a "proper analog output" then. I do know what PWM is. And I said power delivered by PWM is proportional to analogWrite() argument. If you connect a lamp, motor and lots of other stuff they will react on PWM as a "proper analog input". If you connect a true RMS voltmeter it shows voltage level consistent with analogWrite(). If you set PWM base frequency high enough and connect a speaker you can use an analodWrite to play a sound as if it a "proper analog output".

Constant, specific voltage. So if you connect it to an anlog input you get a constant reading, if you connect it to a scope you see a level line. Voltage dividers provide this. Many sensors with analog output do. Current loops are another example.

RMS meters give you an average, a filtered value. Connect a scope to see the real signal.

Incandescent lights and motors use inertia to bridge the gaps - the mass of the motors rotor keeps it running smoothly. LEDs flicker big time but take advantage of the slowness of our eyes to filter that out, so you see a constant glow (feel sorry for chickens having to live under 100 Hz fluorescent light... they can see the flicker!).

There are MCUs out there with analog outputs - look for DAC in the specifications. They do provide a constant voltage output. Note that such a signal is of course not suitable for controlling the speed of motors or the brightness of lights... that's where you want PWM. A DAC is excellent for applications like audio output.

Once again. I know what PWM is. I know how it looks on scope. My point - in many cases PWM can act as a "proper analog output". So analogWrite() name is not too bad.

alesam: Any pin can be used as digital input and digital output and as analog input. Pin marked as PWM can be used as analog output.

Okay now I get it. This solves everything for me.

GolamMostafa:

1. Pin numbers in Black Ink are the physical pins of the IC. Pin numbers with RED Ink are the DPin (digital pin) numbers given by the Arduino IDE. When we say Pin-7, we will refer to the physical pin of the IC and not to DPin of IDE.

2. There are more than one signals attached with a pin. For example: Pin-7 is attched with the following different 5 signals:
(ADC6/PWM/SDA/MOSI)PA6

(1) 4 signals are within a pair of parentheses -- (ADC6/PWM/SDA/MOSI). These are the alternate functions of Pin-7 whcih can (only one function at a time) only be invoked by 'initialization'.

ADC6: Pin-7 will acquire external analog signal for Ch-6 of the internal analog-to-digital converter.
PWM: Pin-7 will output Pulse Width Modulated Signal.
SDA: Pin-7 will work as the bi-directional SDA (Serial Data Line) for the I2C Bus.
MOSI: Pin-7 will work as the 'Master Out Slave In' line of the SPI Port.

(2) One signal named PA6 is lying outside the pair of parentheses. This is the primary function of Pin-7 by default. The pin will work as digital IO (input/output) line to exchange 1-bit data with external devices.

3. Similar interpretations could be made for the signals of the other pins of the MCU.

I noticed that for the ATtiny1634, it has no dedicated pin for Slave Select (SS/CS) for SPI connection. Doesn't it require one or it is just hidden.

My point - in many cases PWM can act as a "proper analog output".

No PWM output is a proper analog output, and the function name is terribly misleading. This is a real problem for beginners.

It is also a real problem for forum members who try to deal with these sorts of misconceptions, and explain to beginners why their idea doesn't work.

This:

Pin marked as PWM can be used as analog output.

is bad advice.

Atia:
I noticed that for the ATtiny1634, it has no dedicated pin for Slave Select (SS/CS) for SPI connection. Doesn't it require one or it is just hidden.

Please see the USI (Universal Serial Interface) Section of the data sheets for details.