I’ve had some success with using the HyperPixel 4.0 with the PiJuice HAT (and the PiJuice Zero pHAT). However I haven’t been able to get the RTC (ds1339) working however, since the dtoverlays don’t expect it on i2c-3.
The symbolic link that is suggested doesn’t seem to work for this, and I’ve had no luck with dtoverlays (i2c-gpio-rtc, or even making my own with target=<&i2c3>; dtbo).
I’ve followed i2c-rtc-gpio the instructions at:
Sadly, no joy - i2cdetect -y 3 yields the address 0x68, but no UU (kernal driver not added).
Since with the HyperPixel you are using the software i2c-bus (i2c-gpio) look at the overlay
i2c-rtc-gpio.
From the README in /boot/overlays:
Name: i2c-rtc-gpio
Info: Adds support for a number of I2C Real Time Clock devices
using the software i2c controller
Load: dtoverlay=i2c-rtc-gpio,<param>=<val>
Params: abx80x Select one of the ABx80x family:
AB0801, AB0803, AB0804, AB0805,
AB1801, AB1803, AB1804, AB1805
ds1307 Select the DS1307 device
ds1339 Select the DS1339 device
ds3231 Select the DS3231 device
m41t62 Select the M41T62 device
mcp7940x Select the MCP7940x device
mcp7941x Select the MCP7941x device
pcf2127 Select the PCF2127 device
pcf2129 Select the PCF2129 device
pcf8523 Select the PCF8523 device
pcf8563 Select the PCF8563 device
rv3028 Select the Micro Crystal RV3028 device
addr Sets the address for the RTC. Note that the
device must be configured to use the specified
address.
trickle-diode-type Diode type for trickle charge - "standard" or
"schottky" (ABx80x only)
trickle-resistor-ohms Resistor value for trickle charge (DS1339,
ABx80x, RV3028)
wakeup-source Specify that the RTC can be used as a wakeup
source
backup-switchover-mode Backup power supply switch mode. Must be 0 for
off or 1 for Vdd < VBackup (RV3028 only)
i2c_gpio_sda GPIO used for I2C data (default "23")
i2c_gpio_scl GPIO used for I2C clock (default "24")
i2c_gpio_delay_us Clock delay in microseconds
(default "2" = ~100kHz)