Messages in this thread | | | Date | Mon, 20 Apr 2009 07:54:01 +0200 | From | Hans-Christian Egtvedt <> | Subject | Re: [PATCH] favr32: improve touchscreen response |
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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
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