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moranf
moranf
Associate II
November 29, 2017
Question

STM32L073 HAL_LCD_Write function

  • November 29, 2017
  • 5 replies
  • 2780 views
Posted on November 29, 2017 at 09:01

Hello,

I'm working on a custom board : stm32l073 + LCD screen ( matrix 4 x 25 ).

I can't understand how to use HAL_LCD_Write function.

As far as I understand I just need 3 parameters in order to write LCD : 

COM: 0-3 

SEG : 0 - 24 

DATA : 0 - 1 ( yes/no )

Or can someone explain the function note :

* @note For LCD glass COM*SEG as 8*40 for example, the LCD common terminals COM[0,7]

* are mapped on 32bits LCD_RAM_REGISTER[0,14] according to rules: COM(n) spread

* on LCD_RAM_REGISTER(2*n) and LCD_RAM_REGISTER(2*n+1).The segment terminals

* SEG[0,39] of COM(n) correspond to LSB bits of related LCD_RAM_REGISTER(2*n)[0,31]

* and LCD_RAM_REGISTER(2*n+1)[0,7]

Please advise

Moran.

#lcd #stm32l073 #hal
This topic has been closed for replies.

5 replies

I
Imen.D
ST Technical Moderator
November 29, 2017
Posted on November 29, 2017 at 09:59

Hello,

HAL_LCD_Write function writes to the LCD RAM memory:

HAL_StatusTypeDef  HAL_LCD_Write (LCD_HandleTypeDef * hlcd, uint32_t RAMRegisterIndex, uint32_t RAMRegisterMask, uint32_t Data) 

You can have a look to the

http://www.st.com/content/ccc/resource/technical/document/user_manual/41/78/8e/63/f9/32/44/12/DM00113898.pdf/files/DM00113898.pdf/jcr:content/translations/en.DM00113898.pdf

User Manual Description of STM32L0 HAL and Low Layer drivers0690X00000608tsQAA.png0690X000006090nQAA.png

Best Regards

Imen

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moranf
moranfAuthor
Associate II
November 29, 2017
Posted on November 29, 2017 at 12:17

Hi Imen,

I've already looked at the HAL user manual, but it doesn't help.

I don't know if it's only me or not but I can't understand what should I write to each parameter of this function.

Thanks in advance.

MarCe
MarCe
Visitor II
March 5, 2019

Hi Moranf I have the same problem.

did you have some solution?

waclawek.jan
waclawek.jan
Super User
March 15, 2020

As Imen pointed out above, HAL_LCD_Write() does not perform any seg/com decoding, it simply writes to one of the LCD module's RAM positions, refer to the LCD chapter in RM.

But the mapping is pretty straighforward: pixels (segments) corresponding to COM0 are in RAM[0] and RAM[1] (i.e. COM0SEG0 is bit 0 in RAM[0], COM0SEG1 is bit 1 in RAM[0] etc.), COM1->RAM2 and RAM3, etc.

JW

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