1.PIC16F876a result register

The 7-bit bit of the ADCON1 status register defines whether the output result is left-aligned or right-aligned. I am confused and don't understand what it is saying. I checked the DataSheet and found the following:

As can be seen from the above diagram, the alignment of the result register is to facilitate us to read the converted data. The diagram is not very detailed, we can take a look at the result register of AD.

The AD result register is 16 bits wide, but six bits are not used, so 10 bits of data are actually read.

2. List of registers related to AD conversion

All registers that control the AD module are shown in the figure below:

AD module basic control registers: ADCON0, ADCON1; mainly manage AD module power-on, clock selection, channel selection, result storage format selection, AD conversion start, etc.

Port configuration register: TRISA, PORTA; mainly defines the analog channel input port and locks the data flow direction (Input=1).

Result saving register.

Related interrupt registers: interrupt master switch, peripheral interrupt control switch, AD interrupt enable, AD interrupt flag;

3. Essentials of AD module design

1. Port configuration:
• Disable pin output driver • Configure pin as analog input pin2
. Configure ADC module:
• Select ADC conversion clock • Configure reference voltage • Select ADC input channel • Select result format • Start ADC module3
. Configure ADC interrupt (can also be polled):
• Clear ADC interrupt flag • Enable ADC interrupt • Enable peripheral interrupt • Enable global interrupt4 
. Wait for required acquisition time5 
. Set GO/DONE to start conversion.
6. Wait for ADC conversion to end by one of the following methods:
• Poll GO/DONE bit • Wait for ADC interrupt (enable interrupt)
7. Read ADC result8
. Clear ADC interrupt flag (if interrupt is enabled, this operation is required).