BS85B12-3 Datasheet, PDF (64/182 Pages) Holtek Semiconductor Inc – Touch Key Flash Type 8-Bit MCU with LCD/LED Driver

BS85B12-3/BS85C20-3
Touch Key Flash MCU with LCD/LED Driver
TM Clock Source
The clock source which drives the main counter in each TM can originate from various sources. The
selection of the required clock source is implemented using the TnCK2~TnCK0 bits in the TM control
registers. The clock source can be a ratio of either the system clock f_SYS or the internal high clock f_H, the
f_TBC clock source or the external TCKn pin. Note that setting these bits to the value 101 will select a
reserved clock input, in effect disconnecting the TM clock source. The TCKn pin clock source is used
to allow an external signal to drive the TM as an external clock source or for event counting.
TM Interrupts
The Compact and Standard type TMs each have two internal interrupts, one for each of the internal
comparator A or comparator P, which generate a TM interrupt when a compare match condition
occurs. As the Enhanced type TM has three internal comparators and comparator A or comparator B or
comparator P compare match functions, it consequently has three internal interrupts. When a TM
interrupt is generated it can be used to clear the counter and also to change the state of the TM output
pin.
TM External Pins
Each of the TMs, irrespective of what type, has one TM input pin, with the label TCKn. The TM input
pin, is essentially a clock source for the TM and is selected using the TnCK2~TnCK0 bits in the
TMnC0 register. This external TM input pin allows an external clock source to drive the internal TM.
This external TM input pin is shared with other functions but will be connected to the internal TM if
selected using the TnCK2~TnCK0 bits. The TM input pin can be chosen to have either a rising or
falling active edge.
The TMs each have one or more output pins with the label TPn. When the TM is in the Compare
Match Output Mode, these pins can be controlled by the TM to switch to a high or low level or to
toggle when a compare match situation occurs. The external TPn output pin is also the pin where the
TM generates the PWM output waveform. As the TM output pins are pin-shared with other function,
the TM output function must first be setup using registers. A single bit in one of the registers
determines if its associated pin is to be used as an external TM output pin or if it is to have another
function. The number of output pins for each TM type and device is different, the details are provided
in the accompanying table.
All TM output pin names have an ²_n² suffix. Pin names that include a ²_1² or ²_2² suffix indicate that
they are from a TM with multiple output pins. This allows the TM to generate a complimentary output
pair, selected using the I/O register data bits.
Device
BS85B12-3
BS85C20-3
CTM
TP0_0, TP0_1
TP0_0, TP0_1
STM
¾
TP2_0, TP2_1
ETM
TP1A, TP1B_0,
TP1B_1, TP1B_2
TP1A, TP1B_0,
TP1B_1, TP1B_2
Registers
TMPC0
TMPC0, TMPC1
TM Output Pins
Rev. 1.00
58
February 1, 2011