WinSystems EBC-LP, Operation Manual

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I/O Ad dress
Off set
Page 0 Page 1 Page 2 Page 3
00H Port 0 I/O Port 0 I/O Port 0 I/O Port 0 I/O
01H Port 1 I/O Port 1 I/O Port 1 I/O Port 1 I/O
02H Port 2 I/O Port 2 I/O Port 2 I/O Port 2 I/O
03H Port 3 I/O Port 3 I/O Port 3 I/O Port 3 I/O
04H Port 4 I/O Port 4 I/O Port 4 I/O Port 4 I/O
05H Port 5 I/O Port 5 I/O Port 5 I/O Port 5 I/O
06H Int_Pend ing Int_Pend ing Int_Pend ing Int_Pend ing
07H Page/Lock Page/Lock Page/Lock Page/Lock
08H N/A Pol_0 Enab_0 Int_ID0
09H N/A Pol_1 Enab_1 Int_ID1
0AH N/A Pol_2 Enab_2 Int_ID2
Reg is ter De tails
Port 0-5 I/O - Each I/O bit in each of the 6 ports can be in di vidu ally pro grammed for in put or
out put. Writing a ‘0’ to a bit position causes the corresponding output pin to go to a High-Impedance
state (pulled high by external 10K ohm resistors). This al lows it to be used as an in put. When used in the
in put mode, a read re flects the in verted state of the I/O pin, such that a high on the pin will read as a '0' in
the reg is ter. Writ ing a '1' to a bit po si tion causes the out put pin to sink cur rent (up to 12mA), ef fec tively
pull ing it low.
INT_PEND ING - This read- only reg is ter re flects the com bined state of the INT_ID0 through
INT_ID2 reg is ters. When any of the lower 3 bits are set, it in di cates that an in ter rupt is pend ing on the
I/O port cor re spond ing to the bit po si tion(s) that are set. Read ing this reg is ter al lows an In ter rupt
Serv ice Rou tine to quickly de ter mine if any in ter rupts are pend ing and which I/O port has a pend ing
in ter rupt.
PAGE/LOCK - This reg is ter serves two pur poses. The up per two bits se lect the reg is ter page in use
as shown here:
D7 D6 Page
0 0 Page 0
0 1 Page 1
1 0 Page 2
1 1 Page 3
Bits 5-0 al low for lock ing the I/O ports. A '1' writ ten to the I/O port po si tion will pro hibit fur ther
writes to the cor re spond ing I/O port.
030530 EBC-LP OPERATIONS MANUAL Page 2-21
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