Philips 8-bit microcontroller with two-clock 80C51 core UM10109 Manual De Usuario

 

© Koninklijke Philips Electronics N.V. 2005. All rights reserved.

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 
P89LPC932A1 through the serial port. This firmware is provided by Philips and embedded 
within each P89LPC932A1 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. 

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 P89LPC932A1 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 
P89LPC932A1 will accept up to 64 (40H) 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 64 (decimal). ISP commands are 
summarized in 

. As a record is received by the P89LPC932A1, 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 P89LPC932A1 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.