Rev. 2.10
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Rev. 2.10
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HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
Enhanced I/O Flash Type 8-Bit MCU with EEPROM
HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
Enhanced I/O Flash Type 8-Bit MCU with EEPROM
UART Module Internal Signal
In addition to the TX and RX external pins described above there are other MCU to UART Module
interconnecting lines that are described in the following table. Note that these lines are internal to
the device and are not bonded to external pins.
MCU to UART Internal Connection
Note: PCK output frequency must be ≤ 12MHz.
UART Module SPI Interface
The MCU communicates with the UART Module via an internal SPI interface. The SPI interface on
this device is comprised of four signals: SCS (SPI Chip Select), SCK (SPI Clock), SDI (Serial Data
Input) and SDO (Serial Data Output). The SPI master, which is the MCU, asserts SCS by pulling it
low to start the data transaction cycle. When the first 8 bits of data are transmitted, SCS should not
return to a high level. Instead, SCS must remain at a low level until the whole 16-bit data transaction
is completed. If SCS is de-asserted, that is returned to a high level before the 16-bit data transaction
is completed, all data bits will be discarded by the UART Module SPI slave.
SPI Timing
Both read and write operations are conducted along the SPI common interface with the following
format:
• Write Type Format: 8-bit command input + 8-bit data input
• Read Type Format: 8-bit command input + 8-bit data output
SDO
SDI
SCK
SCS
A7
A6
A5
A�
A3
A2
A1
A0
D7
D6
D5
D�
D3
D2
D1
D0
Writing Type Format: 8-bit Command Input + 8-bit Data Input