ST92T163R4T1 STMicroelectronics, ST92T163R4T1 Datasheet - Page 94

• Manufacturer Part Number: ST92T163R4T1
• Description: Microcontrollers (MCU) OTP EPROM 20K USB/I2
• Manufacturer: STMicroelectronics

Specifications of ST92T163R4T1

• Data Bus Width: 8 bit, 16 bit
• Program Memory Type: EPROM
• Program Memory Size: 20 KB
• Data Ram Size: 2 KB
• Interface Type: I2C, SCI, USB
• Maximum Clock Frequency: 24 MHz
• Number Of Programmable I/os: 64
• Number Of Timers: 2
• Operating Supply Voltage: 4 V to 5.5 V
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Package / Case: TQFP-64
• Minimum Operating Temperature: 0 C
• On-chip Adc: 8 bit
• Lead Free Status / Rohs Status: No

ST92163 - EXTERNAL MEMORY INTERFACE (EXTMI)
EXTERNAL MEMORY SIGNALS (Cont’d)
Whenever it is sampled low, the System Clock is
stretched and the external memory signals (AS,
DS, DS2, RW, P0 and P1) are released in high-im-
pedance. The external memory interface pins are
driven again by the ST9 as soon as BREQ is sam-
pled high.
BACK (Alternate Function Output, Active low) indi-
cates that the ST9 has relinquished control of the
memory bus in response to a bus request. BREQ
is driven low when the external memory interface
signals are released in high-impedance.
At MCU reset, the bus request function is disabled.
To enable it, configure the I/O port pins assigned
to BREQ and BACK as Alternate Function and set
the BRQEN bit in the MODER register.
6.2.6 PORT 0
If Port 0 (Input/Output, Push-Pull/Open-Drain/
Weak Pull-up) is used as a bit programmable par-
allel I/O port, it has the same features as a regular
port. When set as an Alternate Function, it is used
as the External Memory interface: it outputs the
multiplexed Address 8 LSB: A[7:0] /Data bus
D[7:0].
6.2.7 PORT 1
If Port 1 (Input/Output, Push-Pull/Open-Drain/
Weak Pull-up) is used as a bit programmable par-
allel I/O port, it has the same features as a regular
port. When set as an Alternate Function, it is used
Figure 53. Application Example
94/224
ST9+
RW
P0
AS
DS
P1
A15-A8
A0-A7/D0-D7
D1-D8
OE
LE
LATCH
Q1-Q8
as the external memory interface to provide the 8
MSB of the address A[15:8].
The behavior of the Port 0 and 1 pins is affected by
the BSZ and ETO bits in the EMR1 register. Refer
to the Register description.
6.2.8 WAIT: External Memory Wait
WAIT (Alternate Function Input, Active low) indi-
cates to the ST9 that the external memory requires
more time to complete the memory access cycle. If
bit EWEN (EIVR) is set, the WAIT signal is sam-
pled with the rising edge of the processor internal
clock during phase T1 or T2 of every memory cy-
cle. If the signal was sampled active, one more in-
ternal clock cycle is added to the memory cycle.
On the rising edge of the added internal clock cy-
cle, WAIT is sampled again to continue or finish
the memory cycle stretching. Note that if WAIT is
sampled active during phase T1 then AS is
stretched, while if WAIT is sampled active during
phase T2 then DS is stretched. WAIT is enabled
via software as the Alternate Function input of the
associated I/O port bit (refer to specific ST9 ver-
sion to identify the specific port and pin). Under
Reset status, the associated bit of the port is set to
the bidirectional weak pull-up mode. Refer to Fig-
ure 52
Q0-Q7
A0-A15
E
G
W
64 Kbytes
RAM