Update CHANGELOG

CHANGELOG.md

@@ -5,13 +5,36 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 ### For Users
-#### Added
+- Much improved battery runtime, up to 160% more time without recharging!
+- Integration of the [ctx.graphics] vector graphics renderer!  This
+  means much smoother looking graphics as CTX comes with anti-aliasing!
+- As part of that, we have integrated a new font.  You can also use your own, by
+  replacing `lib/ctx/fira-mono.ttf` with a font of your choice and then
+  rebuilding the firmware.
 - Automatically return from USB storage mode after the host (= your computer)
   ejects the device.
 
+### For Hackers
+- Disable IRQs on core 1 during all Epicardium API calls.  This means API calls
+  are now always safe to use from ISRs.
+- Added an [`epic_sleep()`] API call which can be used as a hint to Epicardium
+  that it can enter a deep-sleep mode.  [`epic_sleep()`] will only return once
+  either the time is up or an interrupt to core 1 is pending.  Pycardium now
+  uses this call for all delays by default.
+- Update MicroPython to v1.17.
+
 ### Internals
-#### Changed
 - Restructured `epicardium/modules` into more sensible subdirectories.
+- Switched the UART peripheral to use the HIRC8 clock.
+- Converted the "personal state" implementation to use the workqueue.
+- Switched the SysTick in Pycardium to use the 32kHz clock source.
+- Made display backlight PWM robust against changes to the MCU's PCLK speed.
+- During tickless idle, lower the core-clock (PCLK) to reduce power consumption.
+- Rewrote the LCD driver.
+- Put the display to sleep when the backlight is off to save power.
+
+[ctx.graphics]: https://ctx.graphics/
+[`epic_sleep()`]: https://firmware.card10.badge.events.ccc.de/epicardium/api.html#c.epic_sleep
 
 
 ## [v1.17] - 2021-04-04 - [R2R Rocket]