Sharp ER-A770 Manual page 52

6. Pseudo SRAM (Standard)
The device is TOSHIBA 4MB SRAM (TC51V8512AFT 512K 8bit) with
access time of 120ns.
6-1. CPU interface
The figure below shows a typical pseudo SRAM interface in the ER-
A770.
ISP2032
Odd side PSRAM
/OWR
/WR
/PCE1_O
/CE
/WSWAP
SD7~SD0
EVEN sid e PSRAM
SD7~SD0
/RSWAP
/WR /HWR
/PCE1_E
/CE
/OE /REFSH
.
REFSH
/RD
Fig. 8
6-2. Pseudo SRAM address
Standard SRAM is decoded as follows by the RASPN1 signal.
700000h 7FFFFFh
The base signal is 2MB. It thus wraparounds with 600000H
6FFFFFH 1MB.
Pseudo SRAM consists of 1 chip for respective even and odd number
addresses. Both of word and byte access from CPU are available.
7. NOR-type flash memory
Here is the explanation for the interface of NOR-type flash memory.
The device is Sharp's LH28F016SU flash memory which consists of
512 K words 16 or 1 MB 8, with 32 blocks of 64 KB.
7-1. CPU interface
The figure below shows a typical interface for the LH28F016SU of the
ER-A770 system.
DATA
ADDRES
H8/510 HWR-
RD-
FVPON
PORT64
NORDY
PORT63
RESET-
MPCA8
FROS1-
/LWR
/HWR
A0
/AS
Gate Arra y
/RESET
RASPN1
D7~D0
D15~D8
/AS
/RESET
RASPN1E
RASPN1
A0
/PR
D Q
CLK
QB
CLR
RASPN1
/RASPN12
or
RASPN2
5V
DQ0~DQ1
VCC
VPP
A0~A2
WE#
OE#
LH28F
016SUT
WP#
RY/BY#
RP#
BYTE#
CE0#
3/5#
CE1#
GND
7-2. Device control
After resetting, the device automatically enters the array read mode
and perform the same action as the usual ROM, thus requiring no
special consideration when reading data.
Data can be written at high speed by using the page buffer.
8. SSP control
The ER-A770 uses flash memory in the place of EPROM, so it is
possible to rewrite the contents of the flash memory in changing the
program. However, since the existing gate array MPCA8 is used, it is
also possible to use the conventional SSP.
8-1. Operation
Like the MPCA7, the MPCA8 adopts the break address register com-
parison method for detecting addresses. The operation of this method
is briefly explained below.
The gate array always compares the break address register (BAR)
built in the gate array, with the address bus to monitor the address
bus.
If both agree, the gate array outputs the NMI signal to the CPU, which
in turn shifts from normal handling to exception handling.
In both the MPCA7 and the MPCA8, SSP is achieved by the above
operation.
The setting of the break address register (BAR) is directly written in
the addresses from FFFF00h to FFFFFFh.
9. Interrupt control
There are roughly two types of interrupts:
Internal interrupts: Controlled inside the CPU
External interrupts: Input into the CPU from outside
9-1. Internal interrupts
Device interrupts built in the CPU are used for the following applica-
tions:
Event factor
SC11 Interrupt source as RS232 : CH8
SC12 Not used (SC1 is used for CKDC interface.)
FRT1 (ICI) INTMCR MCR interrupt (to FT11 terminal)
(OCRA)
(OCRB)
(OVF)
FRT2 (ICI) Standard SHEN event (for CKDC)
(OCRA) Simple IRC timer event
(OCRB) RS232 timer event
(OVF) System timer (53 ms)
TMR (CMA)
(CMB)
(OVF)
WDT (OVF) Drawer open timer
A/D Not used
NMI SSP request
9-2. External interrupts
The following types of external interrupts are available:
NMI (SSP)
IRQ0 (Standard I/O interrupt)
IRQ1 (RS232 interrupt)
IRQ2 (Not Used)
IRQ3 (Used as SCK terminal)
Application