C8051F021 Silicon Laboratories Inc, C8051F021 Datasheet - Page 44

• Manufacturer Part Number: C8051F021
• Description: IC 8051 MCU 64K FLASH 64TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F02xr

Specifications of C8051F021

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: EBI/EMI, SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Ram Size: 4.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x8b, 8x12b; D/A 2x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

C8051F020/1
The Temperature Sensor transfer function is shown in Figure 5.2. The output voltage (V
the Temperature Sensor is selected by bits AMX0AD3-0 in register AMX0SL; this voltage will be amplified by the
PGA according to the user-programmed PGA settings.
5.2.
ADC0 has a maximum conversion speed of 100 ksps. The ADC0 conversion clock is derived from the system clock
divided by the value held in the ADCSC bits of register ADC0CF.
5.2.1. Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start of Conver-
sion Mode bits (AD0CM1, AD0CM0) in ADC0CN. Conversions may be initiated by:
The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete. The fall-
ing edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag (ADC0CN.5). Con-
verted data is available in the ADC0 data word MSB and LSB registers, ADC0H, ADC0L. Converted data can be
either left or right justified in the ADC0H:ADC0L register pair (see example in Figure 5.11) depending on the pro-
grammed state of the AD0LJST bit in the ADC0CN register.
When initiating conversions by writing a ‘1’ to AD0BUSY, the AD0INT bit should be polled to determine when a
conversion has completed (ADC0 interrupts may also be used). The recommended polling procedure is shown below.
44
ADC Modes of Operation
1.
2.
3.
4.
Step 1. Write a ‘0’ to AD0INT;
Step 2. Write a ‘1’ to AD0BUSY;
Step 3. Poll AD0INT for ‘1’;
Step 4. Process ADC0 data.
Writing a ‘1’ to the AD0BUSY bit of ADC0CN;
A Timer 3 overflow (i.e. timed continuous conversions);
A rising edge detected on the external ADC convert start signal, CNVSTR;
A Timer 2 overflow (i.e. timed continuous conversions).
1.000
0.900
0.800
0.700
0.600
0.500
(Volts)
Figure 5.2. Temperature Sensor Transfer Function
-50
0
Rev. 1.4
V
TEMP
50
= 0.00286(TEMP
for PGA Gain = 1
100
C
) + 0.776
TEMP
(Celsius)
) is the PGA input when