ST72C254G2M6 STMicroelectronics, ST72C254G2M6 Datasheet - Page 51

• Manufacturer Part Number: ST72C254G2M6
• Description: IC MCU 8BIT 8K FLASH SOIC-28
• Manufacturer: STMicroelectronics
• Series: ST7r

Specifications of ST72C254G2M6

• Core Processor: ST7
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI
• Peripherals: LVD, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 3.2 V ~ 5.5 V
• Data Converters: A/D 6x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-SOIC (7.5mm Width)
• Controller Family/series: ST7
• No. Of I/o's: 22
• Ram Memory Size: 256Byte
• Cpu Speed: 8MHz
• No. Of Timers: 2
• Rohs Compliant: Yes
• Processor Series: ST72C2x
• Core: ST7
• Data Bus Width: 8 bit
• Data Ram Size: 256 B
• Interface Type: I2C, SPI
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 22
• Number Of Timers: 3 bit
• Operating Supply Voltage: 3.2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Development Tools By Supplier: ST7MDT1-DVP2/US
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8 bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: In Transition

16-BIT TIMER (Cont’d)
12.2.3.5 One Pulse Mode
One Pulse mode enables the generation of a
pulse when an external event occurs. This mode is
selected via the OPM bit in the CR2 register.
The One Pulse mode uses the Input Capture1
function and the Output Compare1 function.
Procedure:
To use One Pulse mode:
1. Load the OC1R register with the value corre-
2. Select the following in the CR1 register:
3. Select the following in the CR2 register:
Then, on a valid event on the ICAP1 pin, the coun-
ter is initialized to FFFCh and the OLVL2 bit is
loaded on the OCMP1 pin, the ICF1 bit is set and
the value FFFDh is loaded in the IC1R register.
Because the ICF1 bit is set when an active edge
occurs, an interrupt can be generated if the ICIE
bit is set.
sponding to the length of the pulse (see the for-
mula in the opposite column).
– Using the OLVL1 bit, select the level to be ap-
– Using the OLVL2 bit, select the level to be ap-
– Select the edge of the active transition on the
– Set the OC1E bit, the OCMP1 pin is then ded-
– Set the OPM bit.
– Select the timer clock CC[1:0] (see
plied to the OCMP1 pin after the pulse.
plied to the OCMP1 pin during the pulse.
ICAP1 pin with the IEDG1 bit (the ICAP1 pin
must be configured as floating input).
icated to the Output Compare 1 function.
Clock Control
event occurs
on ICAP1
Counter
= OC1R
When
When
Bits).
One Pulse mode cycle
OCMP1 = OLVL2
OCMP1 = OLVL1
Counter is reset
ICF1 bit is set
to FFFCh
Table 13
ST72104G, ST72215G, ST72216G, ST72254G
Clearing the Input Capture interrupt request (i.e.
clearing the ICF i bit) is done in two steps:
1. Reading the SR register while the ICF i bit is set.
2. An access (read or write) to the IC i LR register.
The OC1R register value required for a specific
timing application can be calculated using the fol-
lowing formula:
Where:
t
f
PRESC
If the timer clock is an external clock the formula is:
Where:
t
f
When the value of the counter is equal to the value
of the contents of the OC1R register, the OLVL1
bit is output on the OCMP1 pin (see
Notes:
1. The OCF1 bit cannot be set by hardware in
2. When the Pulse Width Modulation (PWM) and
3. If OLVL1=OLVL2 a continuous signal will be
4. The ICAP1 pin can not be used to perform input
5. When One Pulse mode is used OC1R is dedi-
CPU
EXT
One Pulse mode but the OCF2 bit can generate
an Output Compare interrupt.
One Pulse mode (OPM) bits are both set, the
PWM mode is the only active one.
seen on the OCMP1 pin.
capture. The ICAP2 pin can be used to perform
input capture (ICF2 can be set and IC2R can be
loaded) but the user must take care that the
counter is reset each time a valid edge occurs
on the ICAP1 pin and ICF1 can also generates
interrupt if ICIE is set.
cated to this mode. Nevertheless OC2R and
OCF2 can be used to indicate that a period of
time has elapsed but cannot generate an output
waveform because the OLVL2 level is dedi-
cated to One Pulse mode.
= Pulse period (in seconds)
= CPU clock frequency (in hertz)
= Timer prescaler factor (2, 4 or 8 depend-
= Pulse period (in seconds)
= External timer clock frequency (in hertz)
OC i R Value =
ing on the CC[1:0] bits, see
Clock Control
OC i R =
t
*
Bits)
f
EXT
t
PRESC
*
f
CPU
-5
Figure
- 5
Table 13
35).
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