Problem with PCF8563 RTC on Raspberry

Emmanuel Vadot manu at
Mon Feb 4 09:51:21 UTC 2019

On Mon, 4 Feb 2019 10:08:54 +0100
Bernd Walter <ticso at> wrote:

> I'm trying to get the RTC on a Waveshare ARPI600 module running on a
> Raspberry Pi B.
> This is the Overlay I'm using:
> /dts-v1/;
> /plugin/;
> &i2c0 {
> 	 status = "okay";
> 	  rtc: rtc at 51 {
> 		  compatible = "nxp,pcf8563";
> 		  reg = <0x51>;
> 	  };
> };
> IICbus gets probed during boot:
> iicbus0: <OFW I2C bus> on iichb0
> iic0: <I2C generic I/O> on iicbus0
> iicbus0: <unknown card> at addr 0xa2
> When I load the nxprtc moduele I get the following error:
> nxprtc0: <NXP PCF8563 RTC> at addr 0xa2 on iicbus0
> nxprtc0: cannot set up timer
> I wonder if I miss something, e.g. setting GPIO.
> However, for spi0 no GPIO setup was required and the overlay looks
> quite similar.

 Looking at the code it means that the driver didn't managed to talked
to the chip via i2c, the start_timer function is the first time that
i2c transfer is happening.
 Could be either pinmux problems or frequency (default is 100khz so it
should work ok). 
 What pin are you using to connect to the module ?

 Also it seems that the overlay i2c-rtc.dtbo from the Rpi fundation
list this module but I'm unsure how to use this overlay. It is
installed via the rpi-firmware package.

> -- 
> B.Walter <bernd at>
> Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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Emmanuel Vadot <manu at> <manu at>

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