Datasheet

96
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
The TPI is accessed via three pins, as follows:
RESET
: Tiny Programming Interface enable input
TPICLK: Tiny Programming Interface clock input
TPIDATA: Tiny Programming Interface data input/output
In addition, the V
CC
and GND pins must be connected between the external programmer and the device. See Fig-
ure 14-2.
Figure 14-2. Using an External Programmer for In-System Programming via TPI
NVM can be programmed at 5V, only. In some designs it may be necessary to protect components that can not tol-
erate 5V with, for example, series resistors.
14.3.1 Enabling
The following sequence enables the Tiny Programming Interface (see Figure 14-3 for guidance):
• Apply 5V between V
CC
and GND
• Depending on the method of reset to be used:
– Either: wait t
TOUT
(see Table 16-4 on page 118) and then set the RESET pin low. This will reset the
device and enable the TPI physical layer. The RESET
pin must then be kept low for the entire
programming session
– Or: if the RSTDISBL configuration bit has been programmed, apply 12V to the RESET
pin. The RESET
pin must be kept at 12V for the entire programming session
•Wait t
RST
(see Table 16-4 on page 118)
• Keep the TPIDATA pin high for 16 TPICLK cycles
Figure 14-3. Sequence for enabling the Tiny Programming Interface
ATtiny4/5/9/10
TPIDATA/PB0
GND
TPICLK/PB1
PB3/RESET
V
CC
PB2
TPI
CONN
APPLICATION
+5V
RESET
t
RST
TPIDATA
TPICLK
16 x TPICLK CYCLES