Therefore, with these bits, we can select either internal or external reference voltage. But the maximum value of the range depends on the operating voltage or VDD of the pic microcontroller. Reference voltage defines the range of voltage that we can measure with this A/D module. Bit 4 and 5 of ADCON1 register namely, VCFG1: VCFG0 are reference voltage configuration bits for the ADC module.For instance, setting these bits to zero will configure all pins as analog pins. These least significant bits of ADCON1 configure which pin will work as a digital or which pin will work as an analog input pin. From Bit 0-3 PCFG3: PCFG0 are port pins configuration control bits.Even if a programmer tries to read them, they will be read as a zero. Additionally, this register also used to select reference voltage for A/D converter. Therefore, we can select pins functionality either as a digital or ADC pin with this register. But we can use only one function at a time. For example, we can use the same port either as a digital pin or analog pin. First, all GPIO ports of pic microcontroller have multiple functions. Hence, we can use this bit as a flag bit to find either A/D conversion is in progress or completed.ĪDCON1 register has two functions.
This configuration will select analog channel zero or AN0 to get an analog signal from. For example, if we set these four bits to zero: We configure these four bits ( from bit 2-5) to select a specific channel. Firstly, it selects the analog input channel from CH0-CH15 with the help of CHS3: CHS0 bits.ADCON0 has 8 bits and 2 bits (bit 6-7) have no connection or unused. The ADCON0 register stands for Analog to digital converter control register zero. For further information refer to the ADCON2 register section. Note: ADFM bit of ADCON2 Register determines either the result will be left-justified or right-justified. ADRESL Register: Similarly, ASREDL holds 8 least significant bits or most significant bits of 10-bit digital number that is an output of A/D converter or SAR.Therefore, it stores 2 higher/lower bits of 10-bit digital number depending on how we justified the result storage rule. ADRESH Register: This register stores higher or lower bits of digital conversion result after the A/D converter produces a 10-bit digital number.The A/D conversion technique uses a successive approximation (SAR) technique. This digital value is equivalent to its analog input signal. After that, a digital converter changes analog value into a 10-bit digital value. The output of charge/hold capacitor feds to an input of the digital converter. Firstly, each channel accepts analog inputs which charges charge and hold capacitor. How PIC18F ADC Works?ĪDC mainly consists of charge/hold capacitor and successive approximation converter.
ADS1255 PROTEUS LIBRARY SERIES
However, control and configurations registers are the same for every PIC18F series microcontrollers. But the actual number of channels depends on the microcontroller, you are using.
In other words, it can have up to sixteen ADC channels. Each microcontroller can accept up to 16 analog inputs.
0 kommentar(er)
