psd813f3 STMicroelectronics, psd813f3 Datasheet - Page 40

• Manufacturer Part Number: psd813f3
• Description: Flash In-system Programmable Isp Peripherals For 8-bit Mcus
• Manufacturer: STMicroelectronics

PSD813F2, PSD833F2, PSD834F2, PSD853F2, PSD854F2
Input Macrocells (IMC)
The CPLD has 24 Input Macrocells (IMC), one for
each pin on Ports A, B, and C. The architecture of
the Input Macrocells (IMC) is shown in
17., page
vidually configurable, and can be used as a latch,
register, or to pass incoming Port signals prior to
driving them onto the PLD input bus. The outputs
of the Input Macrocells (IMC) can be read by the
MCU through the internal data bus.
The enable for the latch and clock for the register
are driven by a multiplexer whose inputs are a
product term from the CPLD AND Array or the
MCU Address Strobe (ALE/AS). Each product
term output is used to latch or clock four Input
Macrocells (IMC). Port inputs 3-0 can be con-
trolled by one product term and 7-4 by another.
Configurations for the Input Macrocells (IMC) are
specified by equations written in PSDabel (see Ap-
plication Note AN1171). Outputs of the Input Mac-
rocells (IMC) can be read by the MCU via the IMC
buffer.
PORTS, page
40/110
41. The Input Macrocells (IMC) are indi-
See
51.
the
section
entitled
Figure
I/O
Input Macrocells (IMC) can use Address Strobe
(ALE/AS, PD0) to latch address bits higher than
A15. Any latched addresses are routed to the
PLDs as inputs.
Input Macrocells (IMC) are particularly useful with
handshaking communication applications where
two processors pass data back and forth through
a common mailbox.
typical configuration where the Master MCU writes
to the Port A Data Out Register. This, in turn, can
be read by the Slave MCU via the activation of the
“Slave-Read” output enable product term.
The Slave can also write to the Port A Input Mac-
rocells (IMC) and the Master can then read the In-
put Macrocells (IMC) directly.
Note that the “Slave-Read” and “Slave-Wr” signals
are product terms that are derived from the Slave
MCU inputs Read Strobe (RD, CNTL1), Write
Strobe (WR, CNTL0), and Slave_CS.
Figure 18., page 42
shows a