UM10413
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User manual
Rev. 1 — 16 December 2011
177 of 268
NXP Semiconductors
UM10413
MPT612 User manual
19.4.5 A/D Data registers (AD0DR0 to AD0DR7 - 0xE003 4010 to 0xE003 402C)
The A/D Data register holds the result when an A/D conversion is complete, and also
includes the flags that indicate when a conversion is completed and when a conversion
overrun has occurred.
19.5 Operation
19.5.1 Hardware-triggered conversion
If bit BURST in ADCR is logic 0 and the START field contains 010-111, the ADC starts a
conversion when a transition occurs on a selected pin or Timer Match signal. The choices
include conversion on a specified edge of any of 4 Match signals, or conversion on a
specified edge of either of 2 Capture/Match pins. The pin state from the selected pad or
the selected Match signal, XORed with ADCR bit 27, is used in the edge detection logic.
19.5.2 Interrupts
An interrupt request is asserted to the Vectored Interrupt Controller (VIC) when bit DONE
is logic 1. Software can use bit Interrupt Enable for the ADC in the VIC to control whether
this assertion results in an interrupt. DONE is negated when ADDR is read.
19.5.3 Accuracy vs. digital receiver
In order to get accurate voltage readings on the monitored pin, the AD0 function must be
selected in the corresponding Pin Select register (see "Pin Connect Block" in
“Register description” on page 62
). For the pin hosting an ADC input, it is not possible to
have a digital function selected and also get valid ADC readings. An inside circuit
disconnects ADC hardware from the associated pin whenever a digital function is selected
on that pin.
8
ADGINTEN
0
only the individual ADC channels enabled by ADINTEN7:0 generates interrupts 1
1
only the global DONE flag in ADDR is enabled to generate an interrupt
31:9
-
-
reserved, user software must not write logic 1s to reserved bits; value read from
a reserved bit is not defined
n/a
Table 163. A/D Interrupt enable register (AD0INTEN - address 0xE003 400C) bit description
…continued
Bit
Symbol
Value
Description
Reset
value
Table 164. A/D Data registers (ADDR0 to ADDR7 address - 0xE003 4010 to 0xE003 402C) bit description
Bit
Symbol
Description
Reset
value
5:0
-
reserved, user software must not write logic 1s to reserved bits; value read from a reserved
bit is not defined
n/a
15:6
RESULT
if bit DONE is logic 1, this field contains a binary fraction representing voltage on pin AD0,
divided by voltage on pin V
REF
(V/V
REF
). A logic 0 indicates voltage on pin AD0 was less than,
equal to, or close to that on GND
ADC
, while 0x3FF indicates that voltage on AD0 was close to,
equal to, or greater than that on V
REF
.
n/a
29:16
-
reserved, user software must not write logic 1s to reserved bits; value read from a reserved
bit is not defined
n/a
30
OVERRUN logic 1 in burst mode if the results of one or more conversions are lost and overwritten before
the conversion that produced the result in the RESULT bits. Cleared by reading this register.
31
DONE
logic 1 when an A/D conversion completes. Cleared when this register is read.
n/a