Simple question regarding ports

[rngd]

Hi,

Im using ADC with a PIC16F877A.

1. Why do I see people using TRISA = %111111111 when port A is only 6 bits ?

2. When using analog input and ADCIN, is channel 0 to 7 referring to AN0 to AN7 ?


Thank you. I tried searching but couldnt find anything useful because the keywords are not specific enough.

[sayzer]

Hi,
1. Why do I see people using TRISA = %111111111 when port A is only 6 bits ?

They are addicted to it. It does not matter whether you use all 8-bits or only 6-bits.
DataSheet says : TRISA<7:6>are always read as '0'.

Hi,
2. When using analog input and ADCIN, is channel 0 to 7 referring to AN0 to AN7 ?

DataSheet says:

<font color="#000080"><b>BIT </b></font><font color="#FF0000"><b>5</b></font>-<font color="#FF0000"><b>4</b></font>-<font color="#FF0000"><b>3   </b></font>CHS2:CHS0: Analog Channel <font color="#000080"><b>SELECT </b></font>bits
    <font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>0 </b></font>= Channel <font color="#FF0000"><b>0 </b></font>(AN0)
    <font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>1 </b></font>= Channel <font color="#FF0000"><b>1 </b></font>(AN1)
    <font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>0 </b></font>= Channel <font color="#FF0000"><b>2 </b></font>(AN2)
    <font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>1 </b></font>= Channel <font color="#FF0000"><b>3 </b></font>(AN3)
    <font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>0 </b></font>= Channel <font color="#FF0000"><b>4 </b></font>(AN4)
    <font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>0</b></font>-<font color="#FF0000"><b>1 </b></font>= Channel <font color="#FF0000"><b>5 </b></font>(AN5)
    <font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>0 </b></font>= Channel <font color="#FF0000"><b>6 </b></font>(AN6)
    <font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>1</b></font>-<font color="#FF0000"><b>1 </b></font>= Channel <font color="#FF0000"><b>7 </b></font>(AN7)

[rngd]

Oh OK. Thank you very much.