UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 815

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(1) Signal collision
(2) Malfunction of other device
If the dedicated flash memory programmer (output) is connected to a pin (input) of a serial interface connected to
another device (output), signal collision takes place. To avoid this collision, either isolate the connection with the
other device, or make the other device go into an output high-impedance state.
If the dedicated flash memory programmer (output or input) is connected to a pin (input or output) of a serial
interface connected to another device (input), a signal may be output to the other device, causing the device to
malfunction. To avoid this malfunction, isolate the connection with the other device.
78K0/Dx2
Input pin
78K0/Dx2
78K0/Dx2
Figure 26-9. Signal Collision (Input Pin of Serial Interface)
Pin
Pin
In the flash memory programming mode, the signal output by the device
collides with the signal sent from the dedicated flash memory programmer.
Therefore, isolate the signal of the other device.
If the signal output by the 78K0/Dx2 in the flash memory programming
mode affects the other device, isolate the signal of the other device.
If the signal output by the dedicated flash memory programmer in the flash
memory programming mode affects the other device, isolate the signal of
the other device.
Figure 26-10. Malfunction of Other Device
Signal collision
Preliminary User’s Manual U19748EJ1V0UD
CHAPTER 26 FLASH MEMORY
Dedicated flash memory
programmer connection pin
Dedicated flash memory
programmer connection pin
Dedicated flash memory
programmer connection pin
Other device
Output pin
Other device
Other device
Input pin
Input pin
813