Rainbow Electronics ATtiny43U - Manual (Page 151)

151
8048B–AVR–03/09
1. A: Load Command “0000 1000”.
2. B: Load Address Low Byte, 0x00.
3. Set OE to “0”, and BS1 to “1”. The Calibration byte can now be read at DATA.
4. Set OE to “1”.
19.7 Serial Programming
Both the Flash and EEPROM memory arrays can be programmed using the serial SPI bus while
RESET is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and MISO (out-
put). See
Figure 19-7 below.
Figure 19-7. Serial Programming and Verify
Note: If clocked by internal oscillator there is no need to connect a clock source to the CLKI pin.
After RESET is set low, the Programming Enable instruction needs to be executed first before
program/erase operations can be executed
When programming the EEPROM, an auto-erase cycle is built into the self-timed programming
operation (in the Serial mode ONLY) and there is no need to first execute the Chip Erase
instruction. The Chip Erase operation turns the content of every memory location in both the
Program and EEPROM arrays into 0xFF.
Depending on CKSEL Fuses, a valid clock must be present. The minimum low and high periods
for the serial clock (SCK) input are defined as follows:
Low:> 2 CPU clock cycles for f
ck
< 12 MHz, 3 CPU clock cycles for f
ck
>= 12 MHz
High:> 2 CPU clock cycles for f
ck
< 12 MHz, 3 CPU clock cycles for f
ck
>= 12 MHz
Table 19-14. Pin Mapping Serial Programming
Symbol Pins I/O Description
MOSI PB4 I Serial Data in
MISO PB5 O Serial Data out
SCK PB6 I Serial Clock
VCC
GND
SCK
MISO
MOSI
RESET/PA7
+1.8 - 5.5V
PB4
PB5
PB6