3803_15 Datasheet, PDF (110/138 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

3803/3804 Group
q Error check command
Input command code 8016 in the first transfer, and the 3803/3804
group outputs error information from the SDA pin, beginning at the
next falling edge of the serial clock. If the LSB bit of the 8-bit error
information is 1, it indicates that a command error has occurred. A
command error means that some invalid commands other than
commands shown in Table 24 has been input.
When a command error occurs, the serial communication circuit
sets the corresponding flag and stops functioning to avoid an erro-
neous programming or erase. When being placed in this state, the
serial communication circuit does not accept the subsequent serial
clock and data (even including an error check command). There-
fore, if the user wants to execute an error check command,
temporarily drop the VPP pin input to the VPPL level to terminate
the serial input/output mode. Then, place the 3803/3804 group
into the serial I/O mode back again. The serial communication cir-
cuit is reset by this operation and is ready to accept commands.
The error flag alone is not cleared by this operation, so the user
can examine the serial communication circuit’s error conditions
before reset. This examination is done by the first execution of an
error check command after the reset. The error flag is cleared
when the user has executed the error check command. Because
the error flag is undefined immediately after power-on, always be
sure to execute the error check command.
tCH
SCLK
SDA
00000001
Command code input (8016)
“H”
OE
E0
???????
Error flag output
BUSY _{“L”}
Note: When outputting the error flag, the SDA pin is switched for output at the first falling edge of the serial clock. The SDA pin is placed
in the floating state during the period of th(C-E) after the last rising edge of the serial clock (at the 8th bit).
Fig. 100 Timings at error checking
Rev.4.01 Nov 14, 2003 page 108 of 136