Rev. 1.00
80
September 11, 2018
Rev. 1.00
81
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
PTM
PTCK
PTP
PTPI
CCR capture input
CCR output
PTPB
PTM Function Pin Block Diagram
Programming Considerations
The TM Counter Registers and the Capture/Compare CCRA and CCRP registers, 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 and CCRP registers are implemented in the way shown in the following diagram and
accessing these register pairs is carried out in a specific way as described above, it is recommended
to use the "MOV" instruction to access the CCRA and CCRP low byte registers, named xTMAL and
PTMRPL, using the following access procedures. Accessing the CCRA or CCR
P
low byte registers
without following these access procedures will result in unpredictable values.
Data Bus
8-bit Buffer
xTMDH
xTMDL
xTMAH
xTMAL
xTM Counter Register (Read only)
xTM CCRA Register (Read/Write)
PTMRPH
PTMRPL
PTM CCRP Register (Read/Write)
The following steps show the read and write procedures:
•
Writing Data to CCRA or CCRP
♦
Step 1. Write data to Low Byte xTMAL or PTMRPL
– note that here data is only written to the 8-bit buffer.
♦
Step 2. Write data to High Byte xTMAH or PTMRPH
– 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 CCRP
♦
Step 1. Read data from the High Byte xTMDH, xTMAH or PTMRPH
– 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 xTMDL, xTMAL or PTMRPL
– this step reads data from the 8-bit buffer.