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IPC@CHIP SC123/SC143

Hardware Manual V1.06 [18.02.2010]

6.10 Timers

There are two 16-bit programmable timers on the IPC@CHIP. Timer 0 and timer 1 are connected to four

external pins (each one has an input and an output). These two timers can be used to count or time external

events, or to generate non-repetitive or variable-duty-cycle waveforms.

The timer-count value can be read or written at any time, regardless of whether the corresponding timer is

running. The microcontroller increments the value of a timer-count register each time a timer event occurs.

Each timer also has a maximum-count register that defines the maximum value for the timer. When the timer

reaches the maximum value, it resets to 0 during the same clock cycle. The duty cycle and frequency of the

waveform can be set through the RTOS API.

Each timer is serviced on every fourth clock cycle. Therefore, a timer can operate at a maximum speed of one-

quarter of the internal clock frequency. A timer can be clocked externally at the same maximum frequency of

one-fourth of the internal clock frequency. However, because of internal synchronization and pipelining of the

timer circuitry, the timer output takes up to six clock cycles to respond to the clock or gate input.

6.11 Reset

Power On Reset with no external connections is 200ms. RSTOUT# is synchronized with the internal CLKOUT

before it goes inactive. External components (Cdelay and Rdelay) can extend RSTOUT# if needed. The

RSTIN# input is LVTTL and TTL compatible.

3.3V OK

RSTOUT#

GND

RSTIN#

3.3V

1.8V

GNDD1

WDOG#

Internal

Reset

Delay

1.8V OK

SC1x3

RSTOUT#

56K-122K

RSTIN#

3.3V

1 3

I O

Figure 6-18: Internal reset processing

Note: There is no internal observing mechanism for the 3.3V supply voltage. The supply voltage has

to be observed from a external supervisory circuit.

Beck IPC SC123 User Manual

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