attiny167-esxz ATMEL Corporation, attiny167-esxz Datasheet - Page 153

• Manufacturer Part Number: attiny167-esxz
• Description: 8-bit Avr 8-bit Microcontroller Microcontroller With 16k Bytes In-system Programmable Flash And Lin Controller
• Manufacturer: ATMEL Corporation

7728A–AUTO–07/08
Table 14-2.
• Bit 1 – USICLK: Clock Strobe
Writing a one to this bit location strobes the USI Data Register to shift one step and the counter
to increment by one, provided that the USICS1..0 bits are set to zero and by doing so the soft-
ware clock strobe option is selected. The output will change immediately when the clock strobe
is executed, i.e., in the same instruction cycle. The value shifted into the USI Data Register is
sampled the previous instruction cycle. The bit will be read as zero.
When an external clock source is selected (USICS1 = 1), the USICLK function is changed from
a clock strobe to a Clock Select Register. Setting the USICLK bit in this case will select the
USITC strobe bit as clock source for the 4-bit counter (see
• Bit 0 – USITC: Toggle Clock Port Pin
Writing a one to this bit location toggles the USCK/SCL value either from 0 to 1, or from 1 to 0.
The toggling is independent of the setting in the Data Direction Register, but if the PORT value is
to be shown on the pin the DDB2 must be set as output (to one). This feature allows easy clock
generation when implementing master devices. The bit will be read as zero.
When an external clock source is selected (USICS1 = 1) and the USICLK bit is set to one,
writing to the USITC strobe bit will directly clock the 4-bit counter. This allows an early detection
of when the transfer is done when operating as a master device.
USICS1
0
0
0
1
1
1
1
USICS0
Relations between the USICS1..0 and USICLK Setting
0
0
1
0
1
0
1
USICLK
X
0
1
0
0
1
1
USI Data Register Clock
Source
No Clock
Software clock strobe
(USICLK)
Timer/Counter0 Compare
Match
External, positive edge
External, negative edge
External, positive edge
External, negative edge
Table
14-2).
4-bit Counter Clock Source
No Clock
Software clock strobe
(USICLK)
Timer/Counter0 Compare
Match
External, both edges
External, both edges
Software clock strobe (USITC)
Software clock strobe (USITC)
ATtiny167
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