Mitsubishi DS5000TK, DS907x SIP Parallel Programming Concerns, RPC Program Mode Operation, 143

USER'S GUIDE

PARALLEL PROGRAMMING CONCERNS

Dallas Semiconductor highly recommends using the serial load mode for programming the DS5000. It has proven highly reliable and easy to use. In the event that parallel programming is still desirable to some users, several incompatibilities have been discovered in con- ventional device programmers. The following is a sum- mary of these incompatibilities:

1.The DS5000 is a fully CMOS device, and was actu- ally designed to be pin±compatible with the 80C51/87C51 as opposed to the 8051/8751. As a re- sult there is a subtle difference between these two devices. This has to do with the oscillator input pins, XTAL1 and XTAL2. On the CMOS devices, XTAL1 is the pin which is driven in the external drive config- uration. On NMOS devices, XTAL2 is driven for the external clock configuration. This difference has no effect when a crystal is tied to the pins for an external time base. However, many programming systems use the external drive configuration in order to main- tain the ability to program multiple types of devices in a single 40±pin socket. For this reason, the DS5000 will not operate correctly in a 8751±compat- ible socket which uses the external clock mode.

2.The 87C51 data sheet specifies a ªfastº program- ming timing algorithm for programming the locations in its on±chip EPROM memory. This algorithm is identical to the 8751 Program mode specification except for the number and duration of ALE low pulses during a ªProgram Byteº state. There are 25

pulses specified, each with a low time of 90 to 110

μs following by a minimum high time of 10 μs. Since the Parallel Load mode is partially implemented us- ing internal ROM firmware, the 87C51 fast program- ming algorithm is incompatible with the DS5000. Programming systems which implement this algo- rithm will not correctly program a DS5000.

3.Also since the Parallel Program mode is partially firmware based, a minimum recovery time is re- quired between back±to±back Program Byte strobes and between a Program Byte strobe fol- lowed by a Verify strobe.

4.Many programming systems apply VCC voltage dur- ing programming and remove it when programming

is completed. This operation is compatible with the DS5000 if the Power±On Reset time spec (tPOR) is

met before programming begins. Since there is no similar specification on the 8751 or on the 87C51, some programming systems may not meet the DS5000's requirements and Program strobe pulses may not be recognized by the DS5000.

5.The DS5000 is compatible with either the 21V VPP of the 8751 or the 12V VPP of the 87C51. However, some programming systems sample the current that

is drawn during programming on the VCC pin and/or on the VPP pin. An 8751 is specified to draw a maxi- mum of 30 mA of IPP current during programming, while an 87C51 is specified for a maximum of 50 mA.

A DS5000 will draw a maximum of only 15 mA of IPP current during programming. As a result, these pro-

gramming systems may erroneously report that the device is incorrectly installed in the socket.

Because of the limitations cited above, Dallas Semicon- ductor recommends that the Serial Bootstrap Loader be used for initial program loading of the DS5000.

RPC PROGRAM MODE OPERATION

The DS5001FP and DS5002FP series offer high±speed programming mode with many of the benefits of the Serial Loader. Like the Serial mode, it is primarily intended as an in±system technique but can be used in a fixture. This mode uses the RPC (8042) slave inter- face to perform a high speed parallel load. When the PROG pin is pulled to a logic 0, the Bootstrap ROM will begin looking for an ASCII carriage return. This can come in via the serial port or the RPC port. The RPC port is accessed as shown in the section on Parallel I/O. If the RPC buffer is written with a 0Dh, this will cause the loader to respond with its banner and prompt using this same interface. An external microprocessor is assumed to have written and read these values. The RPC loader implements the same command interface and syntax as the Serial Loader. The only difference is the speed at which data can be written, and the lack of a baud rate consideration. As bytes are written into the buffer, they will be acted upon. Handshaking will be used as described in the Parallel I/O section.

The RPC mode requires no super±voltage pulses. The CS, RD, and WR strobes control the transfer of data between the DS5001 and the host. This protocol makes the DS5001 ideal for PC based applications, but any host processor can perform the loading.

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