78M6613 Data Sheet
DS_6613_018
1.5.5 Digital I/O
The device includes up to 10 pins of general purpose digital I/O. When configured as inputs, these pins
are 5V compatible (no current-limiting resistors are needed). On reset or power-up, all DIO pins are
inputs until they are configured for the desired direction under MPU control.
When driving LEDs, relay coils etc., the DIO pins should sink the current into ground (as
shown in Figure 3, right), not source it from V3P3 (as in Figure 3, left).
If more than one input is connected to the same resource, the resources are combined using a logical
OR.
78M6613
78M6613
V3P3D
DIO
V3P3D
DIO
3.3V
3.3V
LED
R
R
LED
GNDD
GNDD
Not recommended
Figure 3: Connecting an External Load to DIO Pins
Recommended
1.5.6 Hardware Watchdog Timer
In addition to the basic watchdog timer included in the 80515 MPU, an independent, robust, fixed-
duration, watchdog timer (WDT) is included in the device. It uses the crystal oscillator as its time base
and must be refreshed by the MPU firmware at least every 1.5 seconds. When not refreshed on time
the WDT overflows, and the part is reset as if the RESET pin were pulled high, except that the I/O RAM
bits will be maintained. 4096 oscillator cycles (or 125 ms) after the WDT overflow, the MPU will be
launched from program address 0x0000. Asserting ICE_E will deactivate the WDT.
1.5.7 Program Security
When enabled, the security feature limits the ICE to global Flash erase operations only. All other ICE
operations are blocked. This guarantees the security of the user’s MPU and CE program code. Security
is enabled by MPU code that is executed in a 32 cycle preboot interval before the primary boot
sequence begins. Once security is enabled, the only way to disable it is to perform a global erase of the
Flash, followed by a chip reset.
1.5.8 Test Ports
TMUXOUT Pin: One out of 16 digital or 8 analog signals can be selected to be output on the TMUXOUT
pin. The function of the multiplexer is described in the applicable firmware documentation.
10
Rev. 1.1
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
