PROGRAMMING THE NONVOLATILE MEMORY

16.8 SLAVE PROGRAMMING MODE

Slave programming mode allows you to program and verify the entire OTPROM array, including the PCCBs and UPROM bits, by using an EPROM programmer.

In this mode, ports 3 and 4 serve as the PBUS, transferring commands, addresses, and data. The least-significant bit of the PBUS (P3.0) controls the command (1 = program word; 0 = dump word) and the remaining 15 bits contain the address of the word to be programmed or dumped. Some port 2 pins provide handshaking signals. The AINC# signal controls whether the address is automatically incremented, enabling programming or dumping sequential OTPROM locations. This speeds up the programming process, since it eliminates the need to generate and decode each sequential address.

NOTE

If a glitch or reset occurs during programming of the security key, an unknown security key might accidentally be written, rendering the device inaccessible for further programming. To prevent this possibility during slave programming, program the rest of the OTPROM array before you program the CCB security-lock bits (CCB0.6 and CCB0.7).

16.8.1 Reading the Signature Word and Programming Voltages

The signature word identifies the device; the programming voltages specify the VPP and VCC volt- ages required for programming. This information resides in the test ROM at locations 2070H, 2072H, and 2073H; however, these locations are remapped to 0070H, 0072H, and 0073H. You can use the dump word command in slave programming mode to read the signature word and pro- gramming voltages at the locations shown in Table 16-8. The external programmer can use this information to determine the device type and operating conditions. You should never write to these locations. The voltages are calculated by using the following equation (after converting the test ROM value to decimal).

Voltage

20

× test ROM value

 

 

= -----------------------------------------------------

 

 

 

 

256

 

 

VCC (40H)

= 20---------

×----64----- = 5 volts

VPP

(0A0H) = 20---------×----160--------- = 12.5 volts

 

256

 

256

16-15

Page 368
Image 368
Intel 8XC196MC, 8XC196MD, 8XC196MH manual Slave Programming Mode, Reading the Signature Word and Programming Voltages