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MichaelPate / XJ-Overhead-Console

Overhead Console Trip Computer for a 1990 Jeep Cherokee XJ. The goal is to display things like gyroscope readings and log GPS points.
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RTC clock too fast #5

Open MichaelPate opened 6 months ago

MichaelPate commented 6 months ago

The real time clock is not configured correctly. Over a ~20 hour span, the RTC ran ahead by 26 minutes. After adjusting the RTC synchronous predivider from 255 to 260, the RTC ran ahead by 17 minutes in 8 hours. The RTC will need to be trimmed, or a different clock selected. An option would be to feed the RTC clock signal to a GPIO pin and measure on an oscilloscope.

MichaelPate commented 6 months ago

Another option is abandoning the onboard RTC for an external module, but this is un-ideal. Such modules need another UART and complicate the hardware circuitry.