Rainbow Electronics T89C51AC2 - Manual (Page 83)

83
T89C51AC2
Rev. B – 19-Dec-01
16.6 ADC Standby Mode When the ADC is not used, it is possible to set it in standby mode by clearing bit ADEN
in ADCON register. In this mode its power dissipation is about 1uW.
16.7 IT ADC management An interrupt end-of-conversion will occurs when the bit ADEOC is activated and the bit
EADC is set. For re-arming the interrupt the bit ADEOC must be cleared by software.
Figure 39. ADC interrupt structure
16.8 Routines examples 1. Configure P1.2 and P1.3 in ADC channels
// configure channel P1.2 and P1.3 for ADC
ADCF = 0Ch
// Enable the ADC
ADCON = 20h
2. Start a standard conversion
// The variable "channel" contains the channel to convert
// The variable "value_converted" is an unsigned int
// Clear the field SCH[2:0]
ADCON &= F8h
// Select channel
ADCON |= channel
// Start conversion in standard mode
ADCON |= 08h
// Wait flag End of conversion
while((ADCON & 01h)!= 01h)
// Clear the End of conversion flag
ADCON &= EFh
// read the value
value_converted = (ADDH << 2)+(ADDL)
3. Start a precision conversion (need interrupt ADC)
// The variable "channel" contains the channel to convert
// Enable ADC
EADC = 1
// clear the field SCH[2:0]
ADCON &= F8h
// Select the channel
ADCON |= channel
// Start conversion in precision mode
ADCON |= 48h
Note: to enable the ADC interrupt:
EA = 1
ADEOC
ADCON.2
EADC
IEN1.1
ADCI