MC68HC05B4 Datasheet, PDF (204/298 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

E.4.3 EEPROM/EPROM/RAM serial bootstrap
For erased EPROM verification, PD4 must be at ‘0’. In this case, erased EPROM verification
executes as described in Section E.4.1 before control is given to the serial routine.
If PD4 is at ‘1’, the program initially checks the state of the security bit. If the security bit is active
(‘0’), the program will not enter serial bootstrap and the red LED will flash. Otherwise the serial
bootstrap program will be executed according to Figure E-3 and Figure E-4.
The serial routine communicates through the SCI with an external host, typically a PC, by means
of an RS232 link at 9600 baud, 8-bit, no parity and full duplex. Refer to Figure E-8 for a schematic
diagram of a suitable circuit.
Note:
Data format is not ASCII, but 8-bit binary, so a complementary program must be run by
the host to supply the required format. Such a program is available for the IBM PC from
Motorola.
14
The EPROM bootstrap routines are used to customise the OTP EPROM. To increase the speed
of programming the 15 kbytes, four bytes are programmed while the data is simultaneously
transmitted back and forward in full duplex. This implies that while 4 bytes are being programmed
the next 4 bytes are received and the preceding 4 bytes are echoed. The format accepted by the
serial loader is as follows:
1) EPROM locations
[address n high] [address n low] [data(n)] [data (n+1)] [data (n+2)] [data (n+3)]
Address n must have the two least significant bits at zero so that n, n+1, n+2 and n+3
have identical most significant bits. These blocks of four bytes do not need to be
contiguous, as a new address is transmitted for each new group.
2) EEPROM1 locations
[address n high] [address n low] [data(n)] [dummy data 1] [dummy data 2] [dummy data 3]
The same four byte protocol of data exchange is used, but only the first data value is
programmed at address n. The three following dummy data values must be sent to be
in agreement with the protocol, but are not significant.
The protocol is as follows:
1) The MC68HC705B16 sends the last two bytes programmed to the host as a
prompt; this also allows the host to verify that programming has been carried
out correctly.
2) In response to the first byte prompt, the host sends the first address byte.
3) After receiving the first address byte, the MC68HC705B16 sends the next
byte programmed.
MOTOROLA
E-16
MC68HC705B16
TPG
MC68HC05B6
Rev. 4