max5450 digitalpot & pic16f877a question

[spacecowboy]

Hello everyone

First of all, since I am a newbie to PICs and this forum, I apologize in advance if I ask any stupid questions

I recently purchased a MAX5450 dual digital potentiometer and planned to use it with PIC16f877a. My problem is I am not sure how to connect them together. I believe that it has an up/down interface, which mean I don't need SPI or I2C, am I correct? Pins that I don't understand and don't know where to connect are; CS, U/D, and INC.

Thanks!!!

 

[zkt_PiratesDen]

You dont need aspi or i2c buss.
Page 7 of the datasheet explains this quite well.
Have you read it ?
there are 2 chip select pins (cs1,cs2) one for each input resistor. The bar over the cs means it is active low. For ex., if cs1 pin is low(logic zero) the corresponding resistor can be changed. If it is high(logic one) it cant be changed. There are several ways to inc/dec the resistor wiper positions ( ike the center-tap on a volume cntrol). They all involve certain pins being held either high or low and other pins transitioning (changing from high to low or from low to high) depending on the desired change. Maxim is well known for their clearly written data sheets. Read the data sheet and see if you can get it from there. If not give me a holler.
zkt

 

[zkt_PiratesDen]

PIN
MAX5451
MAX5453
MAX5455
MAX5450
MAX5452
MAX5454
NAME FUNCTION
1 1 Chip-Select Input of Resistor 1. Drive low to change wiper position W1
through INC and U/D .
—2U/D
Up/Down Control Input. With U/D low, a high-to-low INC transition
decrements wiper position. With U/D high, a high-to-low INC transition
increments wiper position.
2 —U/D1
Up/Down Control Input of Resistor 1. With U/D1 low, a high-to-low INC1
transition decrements wiper position W1. With U/D1 high, a high-to-low
INC1 transition increments wiper position W1.
3 —U/D2
Up/Down Control Input of Resistor 2. With U/D2 low, a high-to-low INC2
transition decrements wiper position W2. With U/D2 high, a high-to-low
INC2 transition increments wiper position W2.
4 3VDD Power Supply
5 4 W1 Wiper Terminal of Resistor 1
6 — H1 High Terminal of Resistor 1
7 5 L1 Low Terminal of Resistor 1
8 6 L2 Low Terminal of Resistor 2
9 — H2 High Terminal of Resistor 2
10 7 W2 Wiper Terminal of Resistor 2
11 8 GND Ground
—9
Wiper Increment Control Input. With CS1 low, a high-to-low transition
increments (U/D high) or decrements (U/D low) wiper position W1. This
applies similarly for CS2 and W2.
12 — INC2 Wiper Increment Control Input. With CS2 low, a high-to-low transition
increments (U/D2 high) or decrements (U/D2 low) wiper position W2.
13 — INC1 Wiper Increment Control Input. With CS1 low, a high-to-low transition
increments (U/D1 high) or decrements (U/D1 low) wiper position W1.
14 10 CS2 Chip-Select Input of Resistor 2. Drive low to change wiper position W2
through INC and U/D .

 

[spacecowboy]

Thank you, zkt

I actually read the datasheet before, but for some reasons it was so confusing at first. Anyhow, Thanks zkt!!

 

[zkt_PiratesDen]

Glad to help.
whats your plan to control the max chip ?
All you need to control the max is a single port. you could use a much simpler and cheaper chip.Also some pics like the f87 have a built in clock which simplifys things a bit( fewer parts)
microhip site has a chip selector to help simplify the selection process ( check the features you want and it shows the the chips having those features.)

 

[nader_rezaei]

hello hello

 

[nader_rezaei]

how create led display 60*60 by max6960 ?
thankful.