What is CLK, DIN, CS pin on LED Dot Matrix like Max7219 8x32. and how the pin's work?

[viery123111]

i tried looking for how these pin work on LED Dot Matrix Max7219 but i coudln't find any resources for this topic. thank you.

[anon73444976]

CLK = clock
DIN = Data In (MOSI, from the POV of the host device)
CS = Chip Select

They're all explained in the MAX7219 datasheet.

[ruilviana]

@viery123111

Max7219

Hi

SPI Interface

The MAX7219 has a four wire SPI interface - clock, data, chip select and ground - making it very simple to connect to a microcontroller.

1. Data - MOSI - Master Output Serial Input. The 7219 is a slave device.
2. Chip select - Load (CSn) - active low Chip select.
3. Clock - SCK
4. Ground.

look if this site help you.

MAX7219 : Learn How to Easily Drive 64 LEDs using 3 wires.

[groundFungus]

A Google search for "max7219 tutorial arduino" will get a lot of information.

[Paul_B]

So your 8 by 32 display uses four chained MAX7219.

Precisely what do you propose to use it for? For alphanumeric displays you probably want the "Parola" library in the IDE, which will have some further information.

[groundFungus]

@Paul_B

the "Parola" library in the IDE

+1 for Parola. Not just alphanumeric, but custom sprite animations, too. Really fun library once you figure it out.

[viery123111]

I mean the function's, what is CLK, CS, DIN really do. like

• CS (Chip Select), this pin choosing the peripheral devices
• CLK (Clock), the clock signal tells the controller inside the led that the logical state on the data line is valid and for use
• DIN (Data In), ????????????

i need knowledge about how these pin's really do

[groundFungus]

CS is the chip select. It tells the chip whether the incoming data is for that chip or not.
Din is the serial data bits being sent.
CLK is the serial clock that shifts the bits into the shift register.

Google" arduino shift register tutorial" to see how synchronous serial data transfer into a shift register works.

[sterretje]

Have you had a look at the datasheet (https://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf)?

This is thetiming diagram from the datasheetthat should basically explain how it works

Under detailed description, you can find the explanation.

@datasheet

For the MAX7219, serial data at DIN, sent in 16-bit
packets, is shifted into the internal 16-bit shift register
with each rising edge of CLK regardless of the state of
LOAD. For the MAX7221, CS must be low to clock data
in or out. The data is then latched into either the digit or
control registers on the rising edge of LOAD/CS.
LOAD/CS must go high concurrently with or after the
16th rising clock edge, but before the next rising clock
edge or data will be lost. Data at DIN is propagated
through the shift register and appears at DOUT 16.5
clock cycles later. Data is clocked out on the falling
edge of CLK. Data bits are labeled D0–D15 (Table 1).
D8–D11 contain the register address. D0–D7 contain
the data, and D12–D15 are “don’t care” bits. The first
received is D15, the most significant bit (MSB).

[PaulRB]

@viery123111

need knowledge about how these pin's really do

If you want to truly understand how these pins work, put the led matrix to the side for a while. Get a 74hc595 chip, 8 LEDs and 8 series resistors and learn how to control each led individually. But do not use the SPI library or the shiftOut() function. Use only digitalWrite() and do not copy the code of others, write it yourself. When you are able to control all 8 LEDs individually, you will understand what the pins you asked about do. After that, you can use shiftOut() and SPI library in the future. No-one writes code digitalWrite() to send data to chips like these, except for education and understanding.

[viery123111]

This make sense for me, thank you so much