[PATCH] favr32: improve touchscreen response

[PATCH] favr32: improve touchscreen response

[Ben Nizette]

The ezLCD+101 board (to which an favr-32 is fitted) has a long,
unshielded, nasty lead between the touch panel and the ads7843 touch
controller.  In order to get satisfactory response then, we need to
employ every noise-reduction trick in the driver's arsenal.  After
extensive fiddling I've found some good settings:

1) We keep vref on all the time to dramatically reduce settling times
(at the cost of a tiny increase in power consumption).

2) Despite 1 the settling time is still non-zero.  500uS is plenty of
time for the signals to settle

3) Despite 1 and 2 there's still a little bit of noise around.  By
setting a pen recheck delay we make the panel feel less touchy and
twitchy.

Someone with more time and patience myself might be able to tune this
numbers further but these settings are now perfectly acceptable for
normal use.

Tested on ezLCD+101 though should only improve response on other ezLCD+/
favr-32 boards too.

Signed-off-by: Ben Nizette <bn@niasdigital.com>

---
 arch/avr32/boards/favr-32/setup.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/avr32/boards/favr-32/setup.c b/arch/avr32/boards/favr-32/setup.c
index 58203d1..f1152fa 100644
--- a/arch/avr32/boards/favr-32/setup.c
+++ b/arch/avr32/boards/favr-32/setup.c
@@ -72,6 +72,10 @@ static struct ads7846_platform_data ads7843_data = {
 	.debounce_max		= 20,
 	.debounce_rep		= 4,
 	.debounce_tol		= 5,
+	
+	.keep_vref_on		= true,
+	.settle_delay_usecs	= 500,
+	.penirq_recheck_delay_usecs = 100,
 
 	/* The ads7843 pendown irq is just connected to regular
 	 * gpio and therefore can only trigger interrupts on
-- 
1.6.0.2

Re: [PATCH] favr32: improve touchscreen response

[Ben Nizette]

On Mon, 2009-04-20 at 12:36 +1000, Ben Nizette wrote:
> +	.keep_vref_on		= true,
> +	.settle_delay_usecs	= 500,
> +	.penirq_recheck_delay_usecs = 100,
>  
>  	/* The ads7843 pendown irq is just connected to regular
>  	 * gpio and therefore can only trigger interrupts on

Whoops, looks like this applies on top of

[PATCH] ads7846: Allow both-edge interrupt mode

Sorry.  Let us know if you want me to rebase :-)

	--Ben.

Re: [PATCH] favr32: improve touchscreen response

[Hans-Christian Egtvedt]

On Mon, 20 Apr 2009 12:36:53 +1000
Ben Nizette <ben@niasdigital.com> wrote:

> The ezLCD+101 board (to which an favr-32 is fitted) has a long,
> unshielded, nasty lead between the touch panel and the ads7843 touch
> controller.  In order to get satisfactory response then, we need to
> employ every noise-reduction trick in the driver's arsenal.  After
> extensive fiddling I've found some good settings:
> 
> 1) We keep vref on all the time to dramatically reduce settling times
> (at the cost of a tiny increase in power consumption).
> 
> 2) Despite 1 the settling time is still non-zero.  500uS is plenty of
> time for the signals to settle
> 
> 3) Despite 1 and 2 there's still a little bit of noise around.  By
> setting a pen recheck delay we make the panel feel less touchy and
> twitchy.
> 
> Someone with more time and patience myself might be able to tune this
> numbers further but these settings are now perfectly acceptable for
> normal use.
> 
> Tested on ezLCD+101 though should only improve response on other
> ezLCD+/ favr-32 boards too.
> 
> Signed-off-by: Ben Nizette <bn@niasdigital.com>
> 

Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>

> ---
>  arch/avr32/boards/favr-32/setup.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/avr32/boards/favr-32/setup.c
> b/arch/avr32/boards/favr-32/setup.c index 58203d1..f1152fa 100644
> --- a/arch/avr32/boards/favr-32/setup.c
> +++ b/arch/avr32/boards/favr-32/setup.c
> @@ -72,6 +72,10 @@ static struct ads7846_platform_data ads7843_data =
> { .debounce_max		= 20,
>  	.debounce_rep		= 4,
>  	.debounce_tol		= 5,
> +	
> +	.keep_vref_on		= true,
> +	.settle_delay_usecs	= 500,
> +	.penirq_recheck_delay_usecs = 100,
>  
>  	/* The ads7843 pendown irq is just connected to regular
>  	 * gpio and therefore can only trigger interrupts on

-- 
Best regards,
Hans-Christian Egtvedt

Re: [PATCH] favr32: improve touchscreen response

[Ben Nizette]

Hi Haavard,

This has hce's ack, any chance of getting it in .31?

Thx,
	--Ben.

On Mon, 2009-04-20 at 12:36 +1000, Ben Nizette wrote:
> The ezLCD+101 board (to which an favr-32 is fitted) has a long,
> unshielded, nasty lead between the touch panel and the ads7843 touch
> controller.  In order to get satisfactory response then, we need to
> employ every noise-reduction trick in the driver's arsenal.  After
> extensive fiddling I've found some good settings:
> 
> 1) We keep vref on all the time to dramatically reduce settling times
> (at the cost of a tiny increase in power consumption).
> 
> 2) Despite 1 the settling time is still non-zero.  500uS is plenty of
> time for the signals to settle
> 
> 3) Despite 1 and 2 there's still a little bit of noise around.  By
> setting a pen recheck delay we make the panel feel less touchy and
> twitchy.
> 
> Someone with more time and patience myself might be able to tune this
> numbers further but these settings are now perfectly acceptable for
> normal use.
> 
> Tested on ezLCD+101 though should only improve response on other ezLCD+/
> favr-32 boards too.
> 
> Signed-off-by: Ben Nizette <bn@niasdigital.com>
> 
> ---
>  arch/avr32/boards/favr-32/setup.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/avr32/boards/favr-32/setup.c b/arch/avr32/boards/favr-32/setup.c
> index 58203d1..f1152fa 100644
> --- a/arch/avr32/boards/favr-32/setup.c
> +++ b/arch/avr32/boards/favr-32/setup.c
> @@ -72,6 +72,10 @@ static struct ads7846_platform_data ads7843_data = {
>  	.debounce_max		= 20,
>  	.debounce_rep		= 4,
>  	.debounce_tol		= 5,
> +	
> +	.keep_vref_on		= true,
> +	.settle_delay_usecs	= 500,
> +	.penirq_recheck_delay_usecs = 100,
>  };
 

Re: [PATCH] favr32: improve touchscreen response

[Haavard Skinnemoen]

Ben Nizette wrote:
> Hi Haavard,
> 
> This has hce's ack, any chance of getting it in .31?

Yeah, should be a good chance :-) Sorry for taking so long.

It doesn't apply, however. I ended up doing this:

diff --git a/arch/avr32/boards/favr-32/setup.c b/arch/avr32/boards/favr-32/setup.c
index 46c9b0a..75f19f4 100644
--- a/arch/avr32/boards/favr-32/setup.c
+++ b/arch/avr32/boards/favr-32/setup.c
@@ -72,6 +72,10 @@ static struct ads7846_platform_data ads7843_data = {
 	.debounce_max		= 20,
 	.debounce_rep		= 4,
 	.debounce_tol		= 5,
+
+	.keep_vref_on		= true,
+	.settle_delay_usecs	= 500,
+	.penirq_recheck_delay_usecs = 100,
 };
 
 static struct spi_board_info __initdata spi1_board_info[] = {

It appears to compile, but please verify that it's still correct.

Haavard

Re: [PATCH] favr32: improve touchscreen response

[Ben Nizette]

On Mon, 2009-07-27 at 13:17 +0200, Haavard Skinnemoen wrote:
> Ben Nizette wrote:
> > Hi Haavard,
> > 
> > This has hce's ack, any chance of getting it in .31?
> 
> Yeah, should be a good chance :-) Sorry for taking so long.
> 
> It doesn't apply, however. I ended up doing this:
> 
> diff --git a/arch/avr32/boards/favr-32/setup.c b/arch/avr32/boards/favr-32/setup.c
> index 46c9b0a..75f19f4 100644
> --- a/arch/avr32/boards/favr-32/setup.c
> +++ b/arch/avr32/boards/favr-32/setup.c
> @@ -72,6 +72,10 @@ static struct ads7846_platform_data ads7843_data = {
>  	.debounce_max		= 20,
>  	.debounce_rep		= 4,
>  	.debounce_tol		= 5,
> +
> +	.keep_vref_on		= true,
> +	.settle_delay_usecs	= 500,
> +	.penirq_recheck_delay_usecs = 100,
>  };
>  
>  static struct spi_board_info __initdata spi1_board_info[] = {
> 
> It appears to compile, but please verify that it's still correct.

Looks good, thanks!

Tested-by: Ben Nizette <bn@niasdigital.com>

> 
> Haavard