ST92F250CV2 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST92F250CV2

8/16-bit single voltage Flash MCU family with RAM, E³ TM (emulated EEPROM), CAN 2.0B and J1850 BLPD

STMicroelectronics 

Device architecture

ST92F124xx/ST92F150Cxx/ST92F150JDV1/ST92F250CV2

Bit 5 = DIV2: Crystal Oscillator Clock Divided by 2.

This bit controls the divide-by-2 circuit operating on the crystal oscillator clock (CLOCK1).

0: Clock divided by 1

1: Clock divided by 2

Bits 4:2 = PRS[2:0]: CPUCLK Prescaler.

These bits load the prescaler division factor for the internal clock (INTCLK). The prescaler

factor selects the internal clock frequency, which can be divided by a factor from 1 to 8.

Refer to the Reset and Clock Control chapter for further information.

Note:

Bit 1 = BRQEN: Bus Request Enable.

0: External Memory Bus Request disabled

1: External Memory Bus Request enabled on BREQ pin (where available).

Disregard this bit if BREQ pin is not available.

Note:

6.3.6

Note:

Bit 0 = HIMP: High Impedance Enable.

When a port is programmed as Address and Data lines to interface external Memory, these

lines and the Memory interface control lines (AS, DS, R/W) can be forced into the High

Impedance state.

0: External memory interface lines in normal state

1: High Impedance state.

Setting the HIMP bit is recommended for noise reduction when only internal Memory is

used.

If the memory access ports are declared as an address AND as an I/O port (for example:

P10... P14 = Address, and P15... P17 = I/O), the HIMP bit has no effect on the I/O lines.

Stack pointers

Two separate, double-register stack pointers are available: the System Stack Pointer and the

User Stack Pointer, both of which can address registers or memory.

The stack pointers point to the “bottom” of the stacks which are filled using the push

commands and emptied using the pop commands. The stack pointer is automatically pre-

decremented when data is “pushed” in and post-incremented when data is “popped” out.

The push and pop commands used to manage the System Stack may be addressed to the

User Stack by adding the suffix “u”. To use a stack instruction for a word, the suffix “w” is

added. These suffixes may be combined.

When bytes (or words) are “popped” out from a stack, the contents of the stack locations are

unchanged until fresh data is loaded. Thus, when data is “popped” from a stack area, the

stack contents remain unchanged.

Instructions such as: pushuw RR236 or pushw RR238, as well as the corresponding

pop instructions (where R236 & R237, and R238 & R239 are themselves the user and

system stack pointers respectively), must not be used, since the pointer values are

62/523

Doc ID 8848 Rev 7

Share Link: