ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 228

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

228
ATmega325/3250/645/6450
As an example, consider the task of verifying a 1.5V ± 5% input signal at ADC channel 3
when the power supply is 5.0V and AREF is externally connected to V
The recommended values from Table 95 are used unless other values are given in the
algorithm in Table 96. Only the DAC and port pin values of the Scan Chain are shown.
The column “Actions” describes what JTAG instruction to be used before filling the
Boundary-scan Register with the succeeding columns. The verification should be done
on the data scanned out when scanning in the data on the same row in the table.
Table 96. Algorithm for Using the ADC
Using this algorithm, the timing constraint on the HOLD signal constrains the TCK clock
frequency. As the algorithm keeps HOLD high for five steps, the TCK clock frequency
has to be at least five times the number of scan bits divided by the maximum hold time,
t
hold,max
Step
1
2
3
4
5
6
7
8
9
10
11
Actions
SAMPLE_
PRELOAD
EXTEST
Verify the
COMP bit
scanned
out to be 0
Verify the
COMP bit
scanned
out to be 1
The lower limit is:
The upper limit is:
ADCEN
1
1
1
1
1
1
1
1
1
1
1
DAC
0x200
0x200
0x200
0x123
0x123
0x200
0x200
0x200
0x143
0x143
0x200
1024 1.5V 0,95 5V
1024 1.5V 1.05 5V
MUXEN
⋅
0x08
0x08
0x08
0x08
0x08
0x08
0x08
0x08
0x08
0x08
0x08
⋅
⋅
⋅
HOLD
1
0
1
1
1
1
0
1
1
1
1
⁄
⁄
=
PRECH
=
291
323
1
1
1
1
0
1
1
1
1
0
1
=
=
0x123
0x143
PA3.
Data
0
0
0
0
0
0
0
0
0
0
0
CC
PA3.
Control
.
0
0
0
0
0
0
0
0
0
0
0
2570A–AVR–09/04
PA3.
Pull-
up_
Enable
0
0
0
0
0
0
0
0
0
0
0