STR911FAM44 STMicroelectronics, STR911FAM44 Datasheet - Page 38

• Manufacturer Part Number: STR911FAM44
• Description: ARM966E-S 16/32-Bit Flash MCU with Ethernet, USB, CAN, AC motor control, 4 timers, ADC, RTC, DMA
• Manufacturer: STMicroelectronics

Specifications of STR911FAM44

• Arm966e-s Risc Core: Harvard architecture, 5-stage pipeline, Tightly-Coupled Memories (SRAM and Flash)

Functional overview
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External memory interface (EMI)
STR91xFA devices in 128-pin and 144-ball packages offer an external memory bus for
connecting external parallel peripherals and memories. The EMI bus resides on ports 7, 8,
and 9 and operates with either an 8 or 16-bit data path. The configuration of 8 or 16 bit
mode is specified by CPU firmware writing to configuration registers at run-time. If the
application does not use the EMI bus, then these port pins may be used for general purpose
I/O as shown in
The EMI has the following features:
●
●
●
●
●
To use all 24 address bits, the following applies: 8 bits of lowest-order data and 8 bits of
lowest-order address are multiplexed on port 8. On port 9, 8-bits of mid-order address are
multiplexed with 8 bits of data, but these 8 data values are always at logic zero on this port
during a write operation, and these 8 data bits are ignored during a read operation. An
external latch device is needed to de-multiplex the mid-order 8 address bits that are
generated on port 8. Port 7 outputs the 8 highest-order address signals directly (not
multiplexed). The output signal on pin EMI_ALE is used to demultiplex the signals on ports 8
and 9, and the polarity of EMI_ALE is programmable. The output signal on pin
Supports static asynchronous memory access cycles, including page mode for non-
mux operation. The bus control signals include:
–
–
–
–
Four configurable memory regions, each with a chip select output (EMI_CS0n ...
EMI_CS3n)
Programmable wait states per memory region for both write and read operations
16-bit multiplexed data mode
address are multiplexed together on ports 8 and 9, while port 7 contains eight more
high-order address signals. The output signal on pin EMI_ALE is used to demultiplex
the signals on ports 8 and 9, and the polarity of EMI_ALE is programmable. The output
signals on pins EMI_BWR_WRLn and EMI_WRHn are the write strobes for the low and
high data bytes respectively. The output signal EMI_RDn is the read strobe for both the
low and high data bytes.
8-bit multiplexed data mode: This is a variant of the 16-bit multiplexed mode.
Although this mode can provide 24 bits of address and 8 bits of data, it does require an
external latch device on Port 8. However, this mode is most efficient when connecting
devices that only require 8 bits of address on an 8-bit multiplexed address/data bus,
and have simple read, write, and latch inputs as shown in
EMI_RDn - read signal, x8 or x16 mode
EMI_BWR_WRLn - write signal in x8 mode and write low byte signal in x16 mode
EMI_WRHn - write high byte signal in x16 mode
EMI_ALE - address latch signal for x8 or x16 mux bus mode with programmable
polarity
Table
8.
Doc ID 13495 Rev 6
(Figure
4): 16 bits of data and 16 bits of low-order
Figure 5
STR91xFAxxx