On 03/04/2019 15:14:24+0000, Flavio Suligoi wrote:
> Hi Alexandre,
>
> > On 03/04/2019 16:52:45+0200, Flavio Suligoi wrote:
> > > The pcf2127 has an automatic battery-low detection function.
> > >
> > > In case of battery-low event, an interrupt generation through
> > > the pin INTn (active low) can be enabled, setting the flag BLIE
> > > in the register Control_3.
> > >
> > > This function is activated by the "battery-low-hw-alarm" DT property.
> > >
> > > Example of use for an NXP i.MX7D board:
> > >
> > > &i2c3 {
> > > clock-frequency = <100000>;
> > > pinctrl-names = "default";
> > > pinctrl-0 = <&pinctrl_i2c3>;
> > > status = "okay";
> > >
> > > pcf2127@51 {
> > > compatible = "nxp,pcf2127";
> > > reg = <0x51>;
> > > battery-low-hw-alarm;
> > > status = "okay";
> > > };
> > > };
> > >
> >
> > So I'm curious, how do you then use that signal? I have a (not yet sent)
> > series adding alarm support for the pcf2127. The issue having BLIE is
> > that then this will prevent the alarm to work properly.
> >
> > So my guess is that you have nINT connected to an LED or something that
> > the user can see?
> >
>
> I'm working on our custom embedded board with an NXP i.MX7D,
> developed here, in Asem (www.asem.it).
> The nINT pin is connected to a GPIO of the MX7 and then
> used by an applicative sw, to generate an alarm for the user.
>
Then, you should probably not enable BLIE because this will cause issues
with the alarm functionnality.. It is certainly enough to use
RTC_VL_READ periodically.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
