P89V51RB2BBC datasheet(21/77 Pages) PHILIPS

21 / 77 page

Philips Semiconductors

P89V51RB2/RC2/RD2

8-bit microcontrollers with 80C51 core

Product data

Rev. 03 — 02 December 2004

21 of 77

9397 750 14341

P89V51RB2/RC2/RD2 through the serial port. This ﬁrmware is provided by Philips

and embedded within each P89V51RB2/RC2/RD2 device. The Philips In-System

Programming facility has made in-circuit programming in an embedded application

possible with a minimum of additional expense in components and circuit board area.

The ISP function uses ﬁve pins (VDD, VSS, TxD, RxD, and RST). Only a small

connector needs to be available to interface your application to an external circuit in

order to use this feature.

7.2.4

Using the In-System Programming

The ISP feature allows for a wide range of baud rates to be used in your application,

independent of the oscillator frequency. It is also adaptable to a wide range of

oscillator frequencies. This is accomplished by measuring the bit-time of a single bit

in a received character. This information is then used to program the baud rate in

terms of timer counts based on the oscillator frequency. The ISP feature requires that

an initial character (an uppercase U) be sent to the P89V51RB2/RC2/RD2 to

establish the baud rate. The ISP ﬁrmware provides auto-echo of received characters.

Once baud rate initialization has been performed, the ISP ﬁrmware will only accept

Intel Hex-type records. Intel Hex records consist of ASCII characters used to

represent hexadecimal values and are summarized below:

:NNAAAARRDD..DDCC<crlf>

In the Intel Hex record, the ‘NN’ represents the number of data bytes in the record.

The P89V51RB2/RC2/RD2 will accept up to 32 data bytes. The ‘AAAA’ string

represents the address of the ﬁrst byte in the record. If there are zero bytes in the

record, this ﬁeld is often set to 0000. The ‘RR’ string indicates the record type. A

record type of ‘00’ is a data record. A record type of ‘01’ indicates the end-of-ﬁle

mark. In this application, additional record types will be added to indicate either

commands or data for the ISP facility.

The maximum number of data bytes in a record is limited to 32 (decimal). ISP

commands are summarized in Table 12. As a record is received by the

P89V51RB2/RC2/RD2, the information in the record is stored internally and a

checksum calculation is performed. The operation indicated by the record type is not

performed until the entire record has been received. Should an error occur in the

checksum, the P89V51RB2/RC2/RD2 will send an ‘X’ out the serial port indicating a

checksum error. If the checksum calculation is found to match the checksum in the

record, then the command will be executed. In most cases, successful reception of

the record will be indicated by transmitting a ‘.’ character out the serial port.

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