EM6517 ETC, EM6517 Datasheet - Page 20

• Manufacturer Part Number: EM6517
• Description: 4 BIT MICROCONTROLLER
• Manufacturer: ETC

7.6 Port C
The EM6517-1 has one globally configurable Input / Output port which is 4 bit wide (only two bits are available
for 24 pin packages). Input or output mode can be set by writing the bit PCIOCntl in RegPCCntl register.
Input data is read directly on the input terminal and put onto the internal data bus. It is not stored in the
RegPCData register. The port C terminal status can be read on address RegPCData even in output mode. Be
aware that the data read on port C is not necessary of the same value as the data stored on RegPCData
register.
At any reset, the RegPCCntl register is cleared, thus setting the port in input mode. During SLEEP mode,
PC[3:0] are in high impedance state.
The port C is globally configurable to act as CMOS or Nch. open drain port , selectable in OPTPCandStr
register (NchOpDPC bit).
7.6.1 Pull-up or Pull-down
On each terminal of PC[3:0] an internal input pull-up (metal mask MPCPU[n]) or pull-down (metal mask
MPCPD[n]) resistor can be connected per metal mask option. Per default the two resistors are in place. In this
case one can chose per software to have either a pull-up, a pull-down or no resistor.
© EM Microelectronic-Marin SA, 09/99, Rev. A/277
20
“0“ = input mode (default), “1“ = output mode. The RegPCData register is used to write output data on port C.
Figure 15. Port C Architecture
Internal Data Bus
DB[n]
Port C Direction Register
Port C Data Register
FOR ENGINEERING ONLY
PCData[n]
Read
PCIOCntl
Read for PC[3:0]
Read
Option Register
Pull-down
NoPdPC
Control
Port C
I / O Terminal
PC[n]
4
Open Drain Option
NchOpDPC
Register
Active
Pull-down
EM6517
Mask Option
MPCPD[n]
mask option
MPCPD[n]
Active Pull-up
in Nch. Open
Drain Mode