Peripheral modules, Addressing peripherals, Atar862-3 – Rainbow Electronics ATAR862-3 User Manual
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ATAR862-3
4556B–4BMCU–02/03
The microcontroller block has various power-down modes. During the sleep mode the
clock for the MARC4 core is stopped. With the NSTOP-bit in the clock management reg-
ister (CM), it is programmable if the clock for the on-chip peripherals is active or stopped
during the sleep mode. If the clock for the core and the peripherals is stopped, the
selected oscillator is switched off. An exception is the 32-kHz oscillator, if it is selected it
runs continuously independent of the NSTOP-bit. If the oscillator is stopped or the
32-kHz oscillator is selected, power consumption is extremely low.
Table 5.
Power-down Modes
Peripheral Modules
Addressing Peripherals
Accessing the peripheral modules takes place via the I/O bus (see Figure 20). The IN or
OUT instructions allow direct addressing of up to 16 I/O modules. A dual register
addressing scheme has been adopted to enable direct addressing of the primary regis-
ter. To address the auxiliary register, the access must be switched with an auxiliary
switching module. Thus, a single IN (or OUT) to the module address will read (or write
into) the module primary register. Accessing the auxiliary register is performed with the
same instruction preceded by writing the module address into the auxiliary switching
module. Byte wide registers are accessed by multiple IN- (or OUT-) instructions. For
more complex peripheral modules, with a larger number of registers, extended address-
ing is used. In this case, a bank of up to 16 subport registers are indirectly addressed
with the subport address. The first OUT-instruction writes the subport address to the
subaddress register, the second IN- or OUT-instruction reads data from or writes data to
the addressed subport.
Mode
CPU
Core
Osc-
Stop
(1)
Brown-
out
Function
RC-oscillator 1
RC-oscillator 2
4-MHz
Oscillator
32-kHz
Oscillator
External
Input
Clock
Active
RUN
NO
Active
RUN
RUN
YES
Power-
down
SLEEP
NO
Active
RUN
RUN
YES
SLEEP
SLEEP
YES
STOP
STOP
RUN
STOP
Note:
1. Osc-Stop = SLEEP and NSTOP and WDL