Datasheet

 2018 Microchip Technology Inc. Data Sheet Complete DS40002060A-page 112
ATtiny4/5/9/10
15.5.8 SKEY - Serial KEY signaling
The SKEY instruction is used to signal the activation key that enables NVM programming. The SKEY instruction is followed
by the 8 data bytes that includes the activation key, as shown in Table 15-9.
15.6 Accessing the Non-Volatile Memory Controller
By default, NVM programming is not enabled. In order to access the NVM Controller and be able to program the non-vola-
tile memories, a unique key must be sent using the SKEY instruction. The 64-bit key that will enable NVM programming is
given in Table 15-10.
After the key has been given, the Non-Volatile Memory Enable (NVMEN) bit in the TPI Status Register (TPISR) must be
polled until the Non-Volatile memory has been enabled.
NVM programming is disabled by writing a logical zero to the NVMEN bit in TPISR.
15.7 Control and Status Space Register Descriptions
The control and status registers of the Tiny Programming Interface are mapped in the Control and Status Space (CSS) of
the interface. These registers are not part of the I/O register map and are accessible via SLDCS and SSTCS instructions,
only. The control and status registers are directly involved in configuration and status monitoring of the TPI.
A summary of CSS registers is shown in Table 15-11.
Table 15-9. The Serial KEY signaling (SKEY) Instruction
Operation Opcode Remarks
Key {8[data}}
1110 0000
Data bytes follow after instruction
Table 15-10. Enable Key for Non-Volatile Memory Programming
Key Value
NVM Program Enable
0x1289AB45CDD888FF
Table 15-11. Summary of Control and Status Registers
Addr. Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0x0F TPIIR Tiny Programming Interface Identification Code
0x0E
...
0x03
Reserved
– – – – – – – –
0x02 TPIPCR
– – – – – GT2 GT1 GT0
0x01 Reserved
– – – – – – – –
0x00 TPISR
– – – – – – NVMEN –