MC68HC705MC4 Datasheet, PDF (17/99 Pages) Motorola, Inc – Microcontrollers

MC68HC705MC4 Specification Rev. 1.5
PA4/PWMB2
1
PA5/PWMA3
2
PA6/PWMB3
3
V_DD
4
PA7
5
V_SS
6
OSC2
7
OSC1
8
RESET
9
IRQ/V_PP
10
PC0/AD0
11
PC1/AD1
12
PC2/AD2
13
PC3/AD3
14
28 _PA3/PWMA2
27 _PA2/PWMB1
26 _PA1/PWMA1
25 PA0
24 _PB7
23 _PB6
22 _PB5/RDI
21 _PB4/TD0
20 _PD7/TCAP2
19 _{PD6/TCMP/TCAP1}
18
PC7/V_REFL
17
PC6/V_REFH
16 _PC5/AD5
15 _PC4/AD4
Figure 2-1: User Mode Pinout
In the User Mode, Port A shares 6 of its 8 I/O lines with the dual channel PWM subsystem.
Port B shares 2 of its 4 I/O lines with the SCI subsystem. Port C shares all of its 8-bit I/O
lines with the A/D subsystem. Port D shares its 2 I/O lines with the 16-bit timer subsystem.
2.2 BOOTLOADER MODE
Bootloader Mode is entered upon the rising edge of RESET if the IRQ/V_PP pin is at V_PP
and the PD7/TCAP2 pin is at logic one. The Bootloader code resides in ROM between
$0F01 to $0FEF. This program handles copying of user code from an external EPROM or
host computer into the on-chip EPROM. Figure 2-2: Programmer Interface to Host
shows the timing required to interface the device being programmed to a host. The
bootloader performs one programming pass at t_EPGM per byte. When programming is
complete, the bootloader code then performs a verify pass. Disable the COP hardware in
bootloader mode.
The external user code addresses must correspond directly with the internal EPROM
addresses.
2.2.1 Bootloader Functions
Three pins are used to select various bootloader functions. These pins are PC0, PC2, and
PC3. PC0 is a SYNC pin, which is used to synchronize the MCU to an off-chip source
driving EPROM data into the MCU. If an external EPROM is used, this pin must be
connected to V_SS. PC2 and PC3 are used to select a programming mode. Two other pins,
PC6 and PC7 are used to drive the PROG LED and the VERF LED respectively. The PC2,
PC3 configurations required to enter the programming modes are shown in Table 2-2:
Bootloader Functions. Alternatively, if PC1 is at a logic high after exiting reset, a jump
to RAM at address $0050 will be executed instead of the bootstrap firmware.
MOTOROLA
Page 8
Section 2: Operating Modes