You are here

Looking for an I2C interface solution that will work with the HD44780 LCD | Cypress Semiconductor

Looking for an I2C interface solution that will work with the HD44780 LCD

Summary: 15 Replies, Latest post by Bob Marlowe on 13 Sep 2016 01:29 AM PDT
Verified Answers: 2
Last post
Log in to post new comments.
Michael Bey's picture
User
29 posts

I have been working with the PCF8574 chip which is set up to work in a 4 bit mode where P0-P3 from the 8574 chip  are connected to D4-D7 of the LCD and P4-P6  are connected to E, R/W and RS. P7 is connected to the Back Plane. I have been trying to use the I2C_LCD component which has not worked since it appears that the data is being transferred in an 8 bit format rather than upper and lower 4 bit nibbles. Are there any software solutions? I am hoping someone can point me in the right direction.

My PC board Layout design would be significantly simpler and I would be able to keep it to a single sided board if I could find an I2C solution rather than having to use the CHAR_LCD component to interface with the LCD.

Thanks

user_1377889's picture
User
10106 posts

Are you mixing up the components? The Character LCD component is using a 4-bit bus (7 signals in total) to interface a hitachi 44780 interface.

The component with I2C interface needs an LCD module with an I2C interface and there is no reason why you cannot get that running. You may even drop the component and program the I2C connection yourself. When you provide us with a link to your LCD module's datasheet we probably could help you a bit further.

 

Bob

 

Michael Bey's picture
User
29 posts

I am including the image of the I2C interface Circuit that I am trying to use with the HD44780 LCD. I need to be able to generate a I2C serial output that simulates the 7 pin parallel output of the CHAR_LCD. I am assuming  the HD44780 LCD will need to be operating in the 4 bit mode with data sent as upper and lower 4 bit nibbles along with the appropriate E, R/W and RS levels for proper command and data transfer.

 

user_1377889's picture
User
10106 posts

You will need an I2C component configured as slave and a a character LCD component together with some glue software. Doesn't look too complicated.

 

Bob

Michael Bey's picture
User
29 posts

I am including the Link to the data sheets for the HD44780 LCD and the PCF8574 I2C interface.

https://www.parallax.com/sites/default/files/downloads/603-00006-Hitachi...

http://www.nxp.com/documents/data_sheet/PCF8574_PCF8574A.pdf

 

Michael Bey's picture
User
29 posts

I am have one of my HD44780 LCD displays hooked up to my bread boarded project using the CHAR_LCD component's  parallel outputs and is working fine. I also have the PCF2119 that came with the CyC8-038 kit hooked up using the I2C_LCD component which is also working as expected. I am looking forward to some help with glue. Are there any Example projects available so I can become more familiar with using the I2C Slave component.

Thanks for your help, Mike

user_1377889's picture
User
10106 posts

In Creator, Start page there is an entry named "Examples and Kits" under which you will see a "Find Code Example" item. Use this to select I2C examples.

 

Bob

Michael Bey's picture
User
29 posts

Last night, I got the SCB_I2c_CommandMaster and Slave project going using the 038 and 042 kits w/o difficulty. I have been studying the code but am not clear on how the cmd variable (which determines which LED will be turned on with the Slave) is declared and assigned a value since this does not appear in any statements of the Slave code or of the Master code  except statements 1062, 1065, 1066 and 1069 of the I2CM_I2C_MASTER.c File where it is declared and a value is assigned.

I am afraid I do not have enough in depth understanding of the PSoc 4 code to generate a New Component that would interface the CHAR_LCD component output to generate a serial output that can be converted back to a parallel output using the 8574 to drive the LCD. Hoping the Glue code will not be outside the scope of information provided by example projects  and documentation readily available on your web site.

Thanks for your continued help, Mike

 

user_1377889's picture
User
10106 posts

You do not need the 8574 chip, this can do the PSoC itself. You do not need to create a new component on the PSoC4, using the I2C and the Character LCD components directly will be quite enough.

I am working now with PSoCs for several years, but I never stuck my nose into one of the generated C-files, there was no need for.

 

Bob

marvkern_1701786's picture
User
1 post

Hi everyone...i am new user here. I worked on I2C using different controllers and as per my experience the component with I2C interface needs an LCD module with an I2C interface and there is no reason why you cannot get that running. You may even drop the component and program the I2C connection yourself. When you provide us with a link to your LCD module's datasheet we probably could help you a bit further.

impedance controlled printed circuit boards

Michael Bey's picture
User
29 posts

I will go ahead an use the I2C_LCD interface and locate and I2C LCD controller. I was going to use the CHAR_LCD component but it will not automatically map to any of the pins of the 28 pin CY8C4245 package. Is there another way mapping the pins?

Thanks Mike
 

 

 

Log in to post new comments.