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litesom:devicetree:lcd [2017/02/15 21:07] filug [Backlight] |
litesom:devicetree:lcd [2017/08/17 11:04] filug [Backlight] |
====== i.MX6UL and LCD display ====== | ====== liteSOM and LCD display ====== |
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| <well> |
| {{:github-mark-32px.png?nolink |}} |
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| Example available on [[https://github.com/grinn-pub/examples|GitHub]]. |
| Check [[https://github.com/grinn-pub/examples/blob/master/configs/grinn_liteboard_lcd_res_defconfig|liteboard LCD + touchscreen]]. |
| </well> |
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<columns 100% 50% - -> | <columns 100% 50% - -> |
* ''PWM'' - <tooltip title="to control LCD display backlight">Pulse Width Modulation</tooltip>. | * ''PWM'' - <tooltip title="to control LCD display backlight">Pulse Width Modulation</tooltip>. |
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Below you can see how to configure [[litesom:liteboard]] to support [[emv:lcd]] module. | Below you can see how to configure [[litesom:liteboard]] to support [[devices:lcd]] module. |
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<alert type="info">Complete example for [[litesom:liteboard]] and [[emv:lcd]] you can find on our [[https://github.com/grinn-pub/examples|GitHub examples repository]].</alert> | <alert type="info">Complete example for [[litesom:liteboard]] and [[devices:lcd]] you can find on our [[https://github.com/grinn-pub/examples|GitHub examples repository]].</alert> |
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On [[evm:lcd]] we are using [[https://riverdi.com/product/rvt7-0a800480tnwr00/|RVT7.0A800480TNWR00]] TFT display produced by [[https://riverdi.com/|Riverdi]]. Below you can find short details about this device: | On [[evm:lcd]] we are using [[https://riverdi.com/product/rvt7-0a800480tnwr00/|RVT7.0A800480TNWR00]] TFT display produced by [[https://riverdi.com/|Riverdi]]. Below you can find short details about this device: |
* touchscreen: resistive. | * touchscreen: resistive. |
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| FIXME LCD part number |
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</columns> | </columns> |
} | } |
</uml> | </uml> |
<newcolumn> | |
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On [[litesom:liteboard]] you can find dedicated LCD backlight boot converter (see [[http://www.ti.com/product/TPS61042|TPS61042]]) controlled by [[:litesom]] via ''PWM2 output'' pin. | |
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{{ :litesom:devicetree:litesom_backlight_driver.png?500 |}} | |
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Backlight can be controlled directly via ''PWM driver'' but additional ''PWM backlight driver'' will <tooltip title="from software point of view">simplify</tooltip> backlight configuration. | |
</columns> | |
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<columns 100% 45% - -> | |
<code> | <code> |
/ { | / { |
</code> | </code> |
<newcolumn> | <newcolumn> |
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| On [[litesom:liteboard]] you can find dedicated LCD backlight boot converter (see [[http://www.ti.com/product/TPS61042|TPS61042]]) controlled by [[:litesom]] via ''PWM2 output'' pin. |
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| {{ :litesom:devicetree:litesom_backlight_driver.png?500 |}} |
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| Backlight can be controlled directly via ''PWM driver'' but additional ''PWM backlight driver'' will <tooltip title="from software point of view">simplify</tooltip> backlight configuration. |
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Node ''backlight'' is documented in [[https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt|pwm-backlight.txt]] file. | Node ''backlight'' is documented in [[https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt|pwm-backlight.txt]] file. |
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Backlight configured as presented here will: | Backlight configured as presented here will: |
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* generate PWM with 200Hz frequency (perion 5000000 ns), | * generate PWM with 200Hz frequency (period 5000000 ns), |
* use ''PWM2'' peripheral as backlight controller, | * use ''PWM2'' peripheral as backlight controller, |
* define eight allowed backlight levels: 0%, 2%, 3%, 6%, 13%, 25%, 50%, 100%, | * define eight allowed backlight levels: 0%, 2%, 3%, 6%, 13%, 25%, 50%, 100%, |
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Node ''pwm2'' is configured as documented in [[https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/pwm/pwm.txt|pwm.txt]]. | Node ''pwm2'' is configured as documented in [[https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/pwm/pwm.txt|pwm.txt]]. |
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</columns> | </columns> |
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