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This program sequentially reads the constant data stored at program memory addresses 0001H to 000CH
#
into the data buffer (
) and outputs the data to Port0A, Port0B, and Port0C (
The constant data is left-shifted one bit. As a result, a high-level data is sequentially output to the Port0A,
Port0B, and Port0C pins.
10.4 DATA BUFFER AND PERIPHERAL HARDWARE
10.4.1 How to Control Peripheral Hardware
The following peripheral hardware units transfer data via the data buffer:
• Image display controller
• A/D converter
• Serial interface
• Horizontal synchronizing signal counter
• 6-bit D/A converter
• Address register
• PLL frequency synthesizer
The peripheral hardware is controlled by setting the data in the peripheral hardware via the data buffer or
reading its data.
Each peripheral hardware unit is provided with a data transfer register called a peripheral register. An
address, called a peripheral address, is allocated to each peripheral hardware unit. Data transfer between the
data buffer and peripheral hardware can be performed by executing a GET or PUT instruction (dedicated to
the peripheral register) for the peripheral register.
The GET and PUT instructions are described below. The peripheral hardware and data buffer functions are
listed in Table 10-1.
GET DBF, p; Reads the data of the peripheral register at address p into the data buffer.
PUT p, DBF; Writes the data of the data buffer to the peripheral register at address p.
There are three types of peripheral registers: Write/read (PUT/GET), write only (PUT), and read only (GET).
Device operation when a GET or PUT instruction is executed for a write only (PUT only) or read only (GET
only) peripheral register is described below.
• When a read (GET) instruction is executed for a write only (PUT only) peripheral register, an undefined
value is returned.
• When a write (PUT) instruction is executed for a read only (GET only), it has no effect.
Be careful when using a 17K series assembler and emulator.
For details, see Section 10.6.
PD17062
$
).
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