Z86E30 Datasheet, PDF (37/66 Pages) Zilog, Inc. – Z8 4K OTP Microcontroller

Zilog
Z86E30/E31/E40
Z8 4K OTP Microcontroller
General-Purpose Registers (GPR). These registers are Counter/Timers. There are two 8-bit programmable
undefined after the device is powered up. The registers counter/timers (T0 and T1), each driven by its own 6-bit
keep their last value after any reset, as long as the reset
occurs in the V_CC voltage-specified operating range. The
programmable prescaler. The T1 prescaler is driven by in-
ternal or external clock sources; however, the T0 prescaler
1
register R254 is general-purpose on Z86E30/E31. R254 is driven by the internal clock only (Figure 27).
and R255 are set to 00H after any reset or STOP-Mode re-
covery.
The 6-bit prescalers can divide the input frequency of the
clock source by any integer number from 1 to 64. Each
RAM Protect. The upper portion of the RAM's address prescaler drives its counter, which decrements the value
spaces 80H to EFH (excluding the control registers) can (1 to 256) that has been loaded into the counter. When the
be protected from reading and writing. This option can be counter reaches the end of count, a timer interrupt request,
selected during the EPROM Programming Mode. After this IRQ4 (T0) or IRQ5 (T1), is generated.
option is selected, the user can activate this feature from
the internal EPROM. D6 of the IMR control register (R251)
is used to turn off/on the RAM protect by loading a 0 or 1,
respectively. A 1 in D6 indicates RAM Protect enabled.
RAM Protect is not available on the Z86E31.
Stack. The Z86E40 external data memory or the internal
register file can be used for the stack. The 16-bit Stack
Pointer (R254-R255) is used for the external stack, which
can reside anywhere in the data memory for ROMless
mode, but only from 4096 to 65535 in ROM mode. An 8-bit
Stack Pointer (R255) is used for the internal stack on the
Z86E30/E31/E40 that resides within the 236 general-pur-
pose registers (R4-R239). SPH (R254) can be used as a
general-purpose register when using internal stack only.
R254 and R255 are set to 00H after any reset or STOP-
Mode Recovery.
DS97Z8X0500
PRELIMINARY
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