PIC16F87T-E/ML【PDF 116/200 页】IC MCU FLASH 4KX14 EEPROM 28QFN

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202

8008H–AVR–04/11

ATtiny48/88

21.3.1

Pin Mapping

The pin mapping is listed in Table 21-7.

21.3.2

Programming Algorithm

When writing serial data to the ATtiny48/88, data is clocked on the rising edge of SCK. When

reading data from the ATtiny48/88, data is clocked on the falling edge of SCK. See Figure 22-9

on page 217 and Figure 22-10 on page 217 for timing details.

To program and verify the ATtiny48/88 in the serial programming mode, the following sequence

is recommended (See Serial Programming Instruction set in Table 21-8 on page 203

Power-up sequence: apply power between V

CC and GND while RESET and SCK are

set to “0”.

– In some systems, the programmer can not guarantee that SCK is held low during

power-up. In this case, RESET must be given a positive pulse after SCK has been

set to '0'. The duration of the pulse must be at least t

RST plus two CPU clock cycles.

See Table 22-3 on page 209 for definition of minimum pulse width on RESET pin,

RST

Wait for at least 20 ms and enable serial programming by sending the Programming

Enable serial instruction to pin MOSI.

The serial programming instructions will not work if the communication is out of syn-

chronization. When in sync. the second byte (0x53), will echo back when issuing the

third byte of the Programming Enable instruction.

– Whether the echo is correct or not, all four bytes of the instruction must be

transmitted.

– If the 0x53 did not echo back, give RESET a positive pulse and issue a new

Programming Enable command.

The Flash is programmed one page at a time. The memory page is loaded one byte at

a time by supplying the 6 LSB of the address and data together with the Load Program

Memory Page instruction.

– To ensure correct loading of the page, the data low byte must be loaded before data

high byte is applied for a given address.

– The Program Memory Page is stored by loading the Write Program Memory Page

instruction with the 7 MSB of the address.

– If polling (RDY/BSY) is not used, the user must wait at least t

WD_FLASH before issuing

the next page (See Table 21-9). Accessing the serial programming interface before

the Flash write operation completes can result in incorrect programming.

The EEPROM can be programmed one byte or one page at a time.

– A: The EEPROM array is programmed one byte at a time by supplying the address

and data together with the appropriate Write instruction. An EEPROM memory

location is first automatically erased before new data is written. If polling (RDY/BSY)

is not used, the user must wait at least t

WD_EEPROM before issuing the next byte (See

Table 21-7.

Pin Mapping Serial Programming

Symbol

Pins

I/O

Description

MOSI

PB3

Serial Data in

MISO

PB4

Serial Data out

SCK

PB5

Serial Clock

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