XC68HC705B32CB Freescale Semiconductor, XC68HC705B32CB Datasheet - Page 53

• Manufacturer Part Number: XC68HC705B32CB
• Description: IC MCU 2.1MHZ 32K OTP 56-DIP
• Manufacturer: Freescale Semiconductor
• Series: HC05r

Specifications of XC68HC705B32CB

• Core Processor: HC05
• Core Size: 8-Bit
• Speed: 2.1MHz
• Connectivity: SCI
• Peripherals: POR, WDT
• Number Of I /o: 32
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: OTP
• Eeprom Size: 256 x 8
• Ram Size: 528 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x8b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 56-SDIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

4
INPUT/OUTPUT PORTS
4
In single-chip mode, the MC68HC05B6 has a total of 24 I/O lines, arranged as three 8-bit ports
(A, B and C), and eight input-only lines, arranged as one 8-bit port (D). Each I/O line is individually
programmable as either input or output, under the software control of the data direction registers.
The 8-bit input-only port (D) shares its pins with the A/D converter, when the A/D converter is
enabled. To avoid glitches on the output pins, data should be written to the I/O port data register
before writing ones to the corresponding data direction register bits to set the pins to output mode.
4.1
Input/output programming
The bidirectional port lines may be programmed as inputs or outputs under software control. The
direction of each pin is determined by the state of the corresponding bit in the port data direction
register (DDR). Each port has an associated DDR. Any I/O port pin is configured as an output if
its corresponding DDR bit is set to a logic one. A pin is configured as an input if its corresponding
DDR bit is cleared to a logic zero.
At power-on or reset, all DDRs are cleared, thus configuring all port pins as inputs. The data
direction registers can be written to or read by the MCU. During the programmed output state, a
read of the data register actually reads the value of the output data latch and not the I/O pin. The
operation of the standard port hardware is shown schematically in
Figure
4-1.
MC68HC05B6
INPUT/OUTPUT PORTS
Freescale
Rev. 4.1
4-1