From 840df9a10386eb6a9547bcc9f48a2a769b934e1a Mon Sep 17 00:00:00 2001 From: Peter Hinch Date: Tue, 14 Sep 2021 06:43:02 +0100 Subject: [PATCH] DS3231 add note on Pyboard Lite. --- DS3231/README.md | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/DS3231/README.md b/DS3231/README.md index 08771e3..d2a35a9 100644 --- a/DS3231/README.md +++ b/DS3231/README.md @@ -79,6 +79,12 @@ to 20ppm. It can benefit from calibration. For this to work reliably on the D a firmware build later than V1.12 is required: use a daily build if a later release is not yet available. +Note that, while the code will run on the Pyboard Lite, this device cannot be +calibrated. This is because its RTC uses an inaccurate RC oscillator whose +frequency is usually beyond the range of the chip's calibration capability. +Even if this is not the case, the lack of stability of RC oscillators makes +calibration a pointless exercise. + The sample below assumes that the DS3231 is connected to the hardware I2C port via I2C(2) but any I2C may be used including soft I2C. Ensure that the Pyboard RTC is set to the correct time and date.