ST92195C STMicroelectronics, ST92195C Datasheet - Page 82

• Manufacturer Part Number: ST92195C
• Description: 48-96 Kbyte Rom Hcmos Mcu With On-screen Display And Teletext Data Slicer
• Manufacturer: STMicroelectronics

7.2 STANDARD TIMER (STIM)
Important Note: This chapter is a generic descrip-
tion of the STIM peripheral. Depending on the ST9
device, some or all of the interface signals de-
scribed may not be connected to external pins. For
the list of STIM pins present on the particular ST9
device, refer to the pinout description in the first
section of the data sheet.
7.2.1 Introduction
The Standard Timer includes a programmable 16-
bit down counter and an associated 8-bit prescaler
with Single and Continuous counting modes capa-
bility. The Standard Timer uses an input pin (STIN)
and an output (STOUT) pin. These pins, when
available, may be independent pins or connected
as Alternate Functions of an I/O port bit.
STIN can be used in one of four programmable in-
put modes:
– event counter,
– gated external input mode,
Figure 46. Standard Timer Block Diagram
n
EXTERNAL
INTERRUPT
STIN
CLOCK2/x
Note 1: Pin not present on all ST9 devices
Note 2: Depending on device, the source of the INPUT & CLOCK CONTROL LOGIC block
STOUT
1
(See Note 2)
may be permanently connected either to STIN or the RCCU signal CLOCK2/x. In devices without STIN and CLOCK2, the
INEN bit must be held at 0.
1
1
CLOCK CONTROL LOGIC
INEN INMD1 INMD2
INPUT
&
INTCLK/4
.
MUX
CONTROL LOGIC
INTERRUPT
STANDARD TIMER
CLOCK
– triggerable input mode,
– retriggerable input mode.
STOUT can be used to generate a Square Wave
or Pulse Width Modulated signal.
The Standard Timer is composed of a 16-bit down
counter with an 8-bit prescaler. The input clock to
the prescaler can be driven either by an internal
clock equal to INTCLK divided by 4, or by
CLOCK2 derived directly from the external oscilla-
tor, divided by device dependent prescaler value,
thus providing a stable time reference independ-
ent from the PLL programming or by an external
clock connected to the STIN pin.
The Standard Timer End Of Count condition is
able to generate an interrupt which is connected to
one of the external interrupt channels.
The End of Count condition is defined as the
Counter Underflow, whenever 00h is reached.
ST92195C/D - STANDARD TIMER (STIM)
OUTPUT CONTROL LOGIC
INTS
INTERRUPT REQUEST
8-BIT PRESCALER
OUTMD1 OUTMD2
STP
DOWNCOUNTER
STH,STL
16-BIT
COUNT
END OF
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