P89C51RC2BASLASH01 datasheet(46/68 Pages) PHILIPS

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Philips Semiconductors

Preliminary data

P89C51RA2/RB2/RC2/RD2xx

80C51 8-bit Flash microcontroller family

8KB/16KB/32KB/64KB ISP/IAP Flash with 512B/512B/512B/1KB RAM

2002 Jul 18

Hardware Activation of the Boot Loader

The boot loader can also be executed by holding PSEN LOW,

EA greater than VIH (such as +5 V), and ALE HIGH (or not connected)

at the falling edge of RESET. This is the same effect as having a

non-zero status byte. This allows an application to be built that will

normally execute the end user’s code but can be manually forced

into ISP operation.

If the factory default setting for the Boot Vector (0FCH) is changed, it

will no longer point to the ISP masked-ROM boot loader code. If this

happens, the only way it is possible to change the contents of the

Boot Vector is through the parallel programming method, provided

that the end user application does not contain a customized loader

that provides for erasing and reprogramming of the Boot Vector and

Status Byte.

After programming the Flash, the status byte should be programmed

to zero in order to allow execution of the user’s application code

beginning at address 0000H.

+5 V (+12 V tolerant)

+5 V

TxD

RxD

VSS

VPP

VCC

TxD

RxD

RST

XTAL2

XTAL1

SU01615

VSS

VCC

P89C51RA2xx

P89C51RB2xx

P89C51RC2xx

P89C51RD2xx

Figure 41. In-System Programming with a Minimum of Pins

In-System Programming (ISP)

The In-System Programming (ISP) is performed without removing

the microcontroller from the system. The In-System Programming

(ISP) facility consists of a series of internal hardware resources

coupled with internal firmware to facilitate remote programming of

the P89C51RA2/RB2/RC2/RD2xx through the serial port. This

firmware is provided by Philips and embedded within each

P89C51RA2/RB2/RC2/RD2xx device.

The Philips In-System Programming (ISP) 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: TxD, RxD, VSS, VCC, and VPP (see

Figure 41). Only a small connector needs to be available to interface

your application to an external circuit in order to use this feature.

The VPP supply should be adequately decoupled and VPP not

allowed to exceed datasheet limits.

Free ISP software is available from the Embedded Systems

Academy: “FlashMagic”

1. Direct your browser to the following page:

http://www.esacademy.com/software/flashmagic/

2. Download Flashmagic

3. Execute “flashmagic.exe” to install the software

Using the In-System Programming (ISP)

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 P89C51RA2/RB2/RC2/RD2xx 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 P89C51RA2/RB2/RC2/RD2xx will accept

up to 16 (10H) 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 16 (decimal). ISP commands are summarized in Table 9.

As a record is received by the P89C51RA2/RB2/RC2/RD2xx, 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 P89C51RA2/RB2/RC2/RD2xx

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 (displaying the contents of the internal

program memory is an exception).

In the case of a Data Record (record type 00), an additional check is

made. A “.” character will NOT be sent unless the record checksum

matched the calculated checksum and all of the bytes in the record

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