Rev. 1.71
68
April 11, 2017
Rev. 1.71
69
April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
PTM
PTPn
PTCKn
Capture Input
TCK Input
Output
PTPnI
PTPnB
Inverting Output
PTM Function Pin Control Block Diagram
Programming Considerations
The TM Counter Registers and the Capture/Compare CCRA register, and CCRP register pair for
Periodic Timer Module, all have a low and high byte structure. The high bytes can be directly
accessed, but as the low bytes can only be accessed via an internal 8-bit buffer, reading or writing
to these register pairs must be carried out in a specific way. The important point to note is that data
transfer to and from the 8-bit buffer and its related low byte only takes place when a write or read
operation to its corresponding high byte is executed.
As the CCRA register and CCRP registers
are
implemented
in
the way shown
in
the following
diagram and accessing the register is carried out CCRP low byte register using the following
access procedures. Accessing the CCRA or CCRP low byte register without following these access
procedures will result
in
unpredictable values.
8-bit Buffer
PTMnDH
PTMnDL
PTMnRPH
PTMnRPL
PTMnAH
PTMnAL
PTM Counter Register (Read only)
PTM CCRA Register (Read/Write)
PTM CCRP Register (Read/Write)
Data Bus
8-bit Buffer
STMDH
STMDL
STM0AH
STM0AL
STM Counter Register (Read only)
STM CCRA Register (Read/Write)
Data Bus
The following steps show the read and write procedures:
• Writing Data to CCRA or PTM CCRP
♦
Step 1. Write data to Low Byte STM0AL PTMnAL or PTMnRPL
–
note that here data is only written to the 8-bit buffer.
♦
Step 2. Write data to High Byte STM0AH PTMnAH or PTMnRPH
–
here data is written directly to the high byte registers and simultaneously data is latched
from the 8-bit buffer to the Low Byte registers.
• Reading Data from the Counter Registers and CCRA or PTM CCRP
♦
Step 1. Read data from the High Byte STM0DH, STM0AH PTMnDH, PTMnAH or PTMnRPH
–
here data is read directly from the High Byte registers and simultaneously data is latched
from the Low Byte register into the 8-bit buffer.
♦
Step 2. Read data from the Low Byte STM0DL, STM0AL PTMnDL, PTMnAL or PTMnRPL
–
this step reads data from the 8-bit buffer.
