P89V51RD2 Datasheet, PDF (19/75 Pages) NXP Semiconductors – 8-bit 80C51 5 V low power 64 kB Flash microcontroller with 1 kB RAM

Philips Semiconductors
P89V51RD2
8-bit microcontrollers with 80C51 core
7.2.3 Power-On reset code execution
Following reset, the P89V51RD2 will either enter the SoftICE mode (if previously
enabled via ISP command) or attempt to autobaud to the ISP boot loader. If this
autobaud is not successful within about 400 ms, the device will begin execution of the
user code.
7.2.4 In-System Programming (ISP)
In-System Programming is performed without removing the microcontroller from the
system. The In-System Programming facility consists of a series of internal hardware
resources coupled with internal firmware to facilitate remote programming of the
P89V51RD2 through the serial port. This firmware is provided by Philips and
embedded within each P89V51RD2 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 (V_DD, V_SS, 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.
7.2.5 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 P89V51RD2 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 P89V51RD2 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 10. As a record is received by the P89V51RD2,
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
P89V51RD2 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.
9397 750 12964
Product data
Rev. 01 — 01 March 2004
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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