AVR Hardware Design Considerations [APPLICATION NOTE]
Atmel-2521M-AVR-Hardware-Design-Considerations_ApplicationNote_092014
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Figure 3-3.
Standard JTAG Connector Used on e.g. AVR JTAGICE mkll and AVR ONE!
3.2.1 Shared Use of JTAG Lines
By creating a JTAG daisy-chain, a single JTAG connector can serve as an ISP interface for several devices. This
principle is shown in
and is explained in further detail in the AVR Tools help file.
Figure 3-4.
JTAG Daisy-Chain
Protection resistors, as shown in
, are necessary if the JTAG lines are also used for other purposes.
For example, if they are used for analog input to the Atmel AVR, there are often analog filters on the lines. If such
filters are present on the JTAG lines, it may be required to eliminate the filter capacitor during programming to
