UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
250 of 362
NXP Semiconductors
UM10208
Chapter 18: LPC2800 ADC
4.7 A/D Power Down Register (ADCPD - 0x8000 5028)
This register is in the System Control address range, but direct affects ADC operation
5.
Operation
5.1 Setting up the ADC
1. If necessary, write 0 to the ADCPD register.
2. If interrupt-driven operation is desired, write a 1 to the ADCINTE register.
3. Write the ADCCON register with 1s in the ENABLE and SELVREF bits.
5.2 Single mode conversion
1. Write the ADCSEL register to select which analog input(s) is (are) to be converted,
and the number of result bits desired for each.
2. Write the ADCCON register with 1s in the ENABLE and START bits, but 0 in the
CSCAN bit.
3. Write the ADCCON register with a 1 in the ENABLE bit, but 0 in the CSCAN and
START bits.
4. Either poll the STATUS bit in the ASCCON register until it is 1, or wait for an interrupt.
5. If interrupt-driven, write 1 to the ADCINTC register.
6. Read the Result register(s) for the analog input(s) that were converted.
5.3 Continuous mode conversion
1. Write the ADCSEL register to select which analog input(s) is (are) to be converted,
and the number of result bits desired for each.
2. Write the ADCCON register with 1s in the ENABLE, CSCAN, and START bits
3. Write the ADCCON register with 1s in the ENABLE and CSCAN bits, but 0 in the
START bit.
4. Either read results as each conversion is completed:
a. Poll the INTSTAT bit in the ASCINTS register until it is 1, or wait for an interrupt
b. If interrupt-driven, write 1 to the ADCINTC register.
c. Read the Result register(s) for the analog input(s) that were converted, then return
to step 4a.
5. Or simply read a result register when the voltage on its input is needed.
Table 283: A/D Power Down Register (ADCPD - 0x8000 5028)
Bit
Symbol
Description
Reset
value
0
ADCPD
A 1 in this bit removes power from the analog A/D circuit. Program this
bit to the opposite of the ENABLE bit in ADDCON, when enabling or
disabling the A/D converter.
0
31:1
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-