Rev. 1.40
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BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
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 xTMnAL
and PTMRPL, using the following access procedures. Accessing the CCRA or CCRP low byte
registers without following these access procedures will result in unpredictable values.
Data Bus
8-�it Buffe�
xTMnDH
xTMnDL
xTMnAH
xTMnAL
xTMn Counte� Registe� (Read only)
xTMn 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 xTMnAL or PTMRPL
– note that here data is only written to the 8-bit buffer.
♦
Step 2. Write data to High Byte xTMnAH 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 xTMnDH, xTMnAH 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 xTMnDL, xTMnAL or PTMRPL
– this step reads data from the 8-bit buffer.