Datasheet

Table Of Contents
Instruction Format
Instruction Byte 1 Byte 2 Byte 3 Byte 4 Operation
Write Fuse Bits
1010 1100 1010 0000 xxxx xxxx iiii iiii
Set bits = “0” to program, “1” to
unprogram. See Table 29-4 for
details.
Write Fuse High
Bits
1010 1100 1010 1000 xxxx xxxx iiii iiii
Set bits = “0” to program, “1” to
unprogram. See Table 29-3 for
details.
Read Fuse Bits
0101 0000 0000 0000 xxxx xxxx oooo oooo
Read Fuse Bits. “0” = programmed,
“1” = unprogrammed. See table
Table 29-4 for details.
Read Fuse High
Bits
0101 1000 0000 1000 xxxx xxxx oooo oooo
Read Fuse high bits. “0” =
programmed, “1” = unprogrammed.
See table Table 29-3 for details.
Read Calibration
Byte
0011 1000 xxxx xxxx 0000 00bb oooo oooo
Read Calibration Byte o at address
b.
Note: 
a = address high bits
b = address low bits
H = 0 – Low byte, 1 – High byte
o = data out
i = data in
x = don’t care
29.9.4. SPI Serial Programming Characteristics
For characteristics of the SPI module, see SPI Timing Characteristics.
Related Links
SPI Timing Characteristics on page 365
29.10. Programming Via the JTAG Interface
Programming through the JTAG interface requires control of the four JTAG specific pins: TCK, TMS, TDI,
and TDO. Control of the Reset and clock pins is not required.
To be able to use the JTAG interface, the JTAGEN fuse must be programmed. The device is default
shipped with the Fuse programmed. In addition, the JTD bit in MCUCSR must be cleared. Alternatively, if
the JTD bit is set, the external reset can be forced low. Then, the JTD bit will be cleared after two chip
clocks, and the JTAG pins are available for programming. This provides a means of using the JTAG pins
as normal port pins in running mode while still allowing In-System Programming via the JTAG interface.
Note that this technique can not be used when using the JTAG pins for Boundary-scan or On-chip Debug.
In these cases the JTAG pins must be dedicated for this purpose.
As a definition in this data sheet, the LSB is shifted in and out first of all Shift Registers.
29.10.1. Programming Specific JTAG Instructions
The instruction register is 4-bit wide, supporting up to 16 instructions. The JTAG instructions useful for
Programming are listed below.
Atmel ATmega32A [DATASHEET]
Atmel-8155I-ATmega32A_Datasheet_Complete-08/2016
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