Advertisement
-729
EV80C196KB Microcontroller Evaluation Board User's Manual
as a digital input, it is recommended that the capacitors be removed, and the resis-
tors replaced with wires. For additional connection information refer to figure 7 or
the schematics in appendix A. The ground and power planes beneath the analog
circuitry (Dl , D2, R3, C2, U3, U4, JPI and the analog connections on the
80Cl96KB) are isolated from the digital power and ground planes of the board to
keep noise from the analog inputs.
Decoding
The decoding logic on the EWOCl96KB board serves three purposes; to provide
Chip-Enable signals to memory and peripheral devices, to select the buswidth for
the device(s) being accessed and to provide wait-states for slow devices. This
section is provided in case you need to modify the memory configuration of the
EV80Cl96KB board. It is not necessary to understand this section for normal usage
of the board.
The heart of the decoding logic is U12, a 24-pin 5AC312 Intel EPLD or a C22VlO
programmable logic array which is socketed to allow easy changes. For the sake of
convenience it will be referred to as "the EPLD" throughout this text. The EPLD
uses latched addresses A8-Al5 along with CLKOUT, HLDA#, RESET# and STALE
(STretched ALE) from the 8OCl96KB as decode inputs.
There are 4 enable outputs from the EPLD, all of which are low-level true, however
only one should be true at a time to avoid bus contention. They are decoded from
the address lines, and an internally-latched signal called MAP. MAP is cleared
when the RESET# input is true, and set when the Monitor EPROMs are accessed in
the address range 1 DOOH-I DFFH. MAP will always be set when the board is in the
USER mode.
pin 21 = CEO
Enables memory in Ul and U8
(monitor EPROM as shipped).
CEO
= (ADDRESS RANGE 2000H - 27FF and NOT MAP)
or ADDRESS RANGE OH - FFH
or ADDRESS RANGE 1 DOOH - 1 DFFH
pin 22 = CEl
Enables memory in U6 and U13
(user 16-bit ROMsim/RAM as shipped).
CEl
= (ADDRESS RANGE 2000H - 27FFH and MAP)
or ADDRESS RANGE 2800H - 5FFFH
pin 15-CE2
Enables memory in U14
(user 8-bit ROMsim/RAM as shipped).
CE2
= ADDRESS RANGE 6000H - 7FFFH
pin 14 - CS510 Enables U20, the 82510 UART, which is
used for host communications.
CS510 = ADDRESS RANGE 1 EOOH - 1 EFFH
Advertisement
