RTC works in emulation, fails in real hardware

[Candid-Moe]

I wrote this little Forth word that execute a SYSCALL 22 to get current time and date.

8 buffer: sys-date
: date ( -- )
    22 sys-date 0 0  ( HL DE BC A registers pushed into the stack )
    z80-syscall         ( do the syscall and put the registers in the stack HL DE BC A )
    ." Return code " . cr
    ." Date " sys-date 8 dump cr
    ;

The word works fine in emulation:

But in the real Zeal 8-bit board, it doesn't work:

The board has a CR2032 battery installed for the RTC (is that necessary) . The voltage is 2.97 v

The boot screen doesn't show an active timer:

How to test

You can test in emulation using https://github.com/Candid-Moe/Zorth/blob/main/prod/zorth.bin

For test in real hardware, use https://github.com/Candid-Moe/Zorth/blob/main/prod/os_with_romdisk.img

[Zeal8bit]

Hello @Candid-Moe !

What you did is correct, I suspect the RTC is stopped in your case. When you put in a CR battery, the RTC won't start automatically, it needs to be setup. The bit 7 of its register 00 needs to be cleared. This needs to be done every time the RTC battery runs out. The getdate syscall doesn't show this register 0's bit 7.

You have two solutions here, from easiest to hardest:

• Use the Test hardware option in the bootloader, which will clear this bit in the RTC automatically. (It will show Disabled (no battery?) but will enable it right after)
• Set the date via the date command on Zeal 8-bit OS command prompt.
• Write an I2C routine in your program that clears bit 7 of register 0

[Candid-Moe]

The "Test Hardware" fixed the problem. Now the clock is ticking but I can't change the date&time. Working on it.