ATtiny20 Atmel Corporation, ATtiny20 Datasheet - Page 170

• Manufacturer Part Number: ATtiny20
• Manufacturer: Atmel Corporation

Specifications of ATtiny20

• Flash (kbytes): 2 Kbytes
• Pin Count: 14
• Max. Operating Frequency: 12 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 5
• Hardware Qtouch Acquisition: Yes
• Max I/o Pins: 12
• Ext Interrupts: 12
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.12
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

19.4.5
19.5
19.6
19.6.1
19.6.2
19.7
19.7.1
170
Self programming
External Programming
Register Description
ATtiny20
Writing NVM Lock Bits
Entering External Programming Mode
Exiting External Programming Mode
NVMCMD – Non-Volatile Memory Command Register
The algorithm for writing the Lock bits is as follows.
The ATtiny20 doesn't support internal programming.
The method for programming the Non-Volatile Memories by means of an external programmer is
referred to as external programming. External programming can be done both in-system or in
mass production.
The Non-Volatile Memories can be externally programmed via the Tiny Programming Interface
(TPI). For details on the TPI, see
external programmer can access the NVM control and status registers mapped to I/O space and
the NVM memory mapped to data memory space.
The TPI must be enabled before external programming mode can be entered. The following pro-
cedure describes, how to enter the external programming mode after the TPI has been enabled:
Refer to the Tiny Programming Interface description on
of enabling the TPI and programming the NVM.
Clear the NVM enable bit to disable NVM programming, then release the RESET pin.
See NVMEN bit in
• Bits 7:6 – Res: Reserved Bits
These bits are reserved and will always read as zero.
Bit
0x33
Read/Write
Initial Value
1. Write the DWORD_WRITE command to the NVMCMD register.
2. Write the lock bits value to the Non-Volatile Memory Lock Byte location. This is the low
3. Start the NVM Lock Bit write operation by writing a dummy byte to the high byte of the
4. Wait until the NVMBSY bit has been cleared.
1. Make a request for enabling NVM programming by sending the NVM memory access
2. Poll the status of the NVMEN bit in TPISR until it has been set.
byte of the Non-Volatile Memory Lock Word.
NVM Lock Word location.
key with the SKEY instruction.
R
7
–
0
“TPISR – Tiny Programming Interface Status Register” on page
R
6
–
0
R/W
5
0
“Programming Interface” on page
R/W
4
0
R/W
NVMCMD[5:0]
3
0
R/W
page 152
2
0
R/W
1
0
for more detailed information
152. Using the TPI, the
R/W
0
0
NVMCMD
8235B–AVR–04/11
162.