
22.3 Serial PROM Mode Setting
22.3.1
Serial PROM mode control pins
To execute on-board programming, activate the serial PROM mode.
Table 22-2 shows the pin setting used to
activate the serial PROM mode.
Table 22-2 Serial PROM Mode Setting
Pin
Setting
RXD0 / SI0 / P21 pin
H level
TXD0 / SO0 / P20 pin
H level
MODE, RESET pin
Note:Before you activate the serial PROM mode, you must set the RXD0/SI0/P21 and TXD0/SO0/P20 pins to high
(H) level by using a pull-up resistor.
Table 22-3 Pin Functions in Serial PROM Mode
Pin name
(in serial PROM mode)
Input/out-
put
Function
Pin name (in MCU mode)
TXD0 / SO0
Output
Serial PROM mode control/serial data output
(See note 1)
TXD0 / SO0 / P20
RXD0 / SI0
Input
Serial PROM mode control/serial data input
RXD0 / SI0 / P21
RESET
Input
Serial PROM mode control
RESET
MODE
Input
Serial PROM mode control
MODE
SCLK0
Input
Serial clock input (if SIO is used)
These ports are in the high-impedance state in the serial
PROM mode. If the UART is used, the port input is phys-
ically fixed to a specified input level in order to prevent a
penetration current. To enable the port input, the
SPCR<PIN1> must be set to "1" by operating the RAM
loader control program.
SCLK0
VDD
Power
supply
3.0 V to 3.6 V
AVDD
Power
supply
Connect to VDD.
VSS
Power
supply
0 V
AVSS
Power
supply
Connect to VSS.
VAREF
Power
supply
Leave open or apply reference voltage.
Input/output port other than
RXD0 and TXD0
Input/
output
These ports are in the high-impedance state in the serial PROM mode. The port input is physically
fixed to a specified input level in order to prevent a penetration current (the port input is disabled). To
enable the port input, the SPCR<PIN0> must be set to "1" by operating the RAM loader control pro-
gram.
XIN
Input
Connect a resonator to make these pins self-oscillate.
XOUT
Output
Note 1: If other parts are mounted on a user board, they may interfere with data being communicated through these communication
pins during on-board programming. It is recommended that these parts be somehow isolated to prevent the pins from
being affected.
TMP89FH46L
22. Serial PROM Mode
22.3 Serial PROM Mode Setting
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