AN2556

Modified features

13/35

Port1 additional channels

A new multiplexer selects between up to 16 + 8 analog input channels (alternate functions of

Port 5 and Port1). The selection of Port1 or Port5 as inputs of ADC is made via the

ADCMUX bit and bit 0 of XMISC register. By default the multiplexer selects Port5, so there is

no impact on the software with regard to ST10F269Zx implementation. Note that XMISCEN

and bit 10 of the XPERCON register must be set in order to have access to the XMISC

register.

1.5

Real time clock

The RTC module can be clocked by two different sources: The main oscillator (pins XTAL1

and XTAL2) or the 32 kHz low power oscillator (pins XTAL3 and XTAL4). Selection of the

clocking can be made via an additional bit in the RTCCON register.

1.5.1

Hardware impacts

Check the usage of pins XTAL3 and XTAL4 (143 and 144 respectively).

1.5.2

Software impacts

The address range of the RTC registers have been modified from 00’EC00h - 00’ECFFh on

the ST10F269Zx to 00’EE00h - 00’EEFFh on ST10F273Z4. This relocation has no impact if

the software uses register names defined by the toolchain and if the CPU selection is

changed to ST10F273Z4. If the software was using the address of the RTC register directly,

it must be modified according to new mapping.

In the ST10F269Zx, both byte and word accesses were allowed for the RTC module. In the

ST10F273Z4, only word accesses are possible.

Check that the code is not creating byte accesses to the RTC module.

In addition, new bits(OFF32, OSC) have been added into the RTCCON register. There is no

impact if the code was not writing to the upper part of the RTCCON register which was

reserved.

The handling of the RTCAIR and RTCSIR flags (bit 2 and 0 of RTCCON register

respectively) is also changed:

XMISC (EB46h)

XREG

Reset value: --00h

15

14

13

12

11

10

9876

54

3210

Reserved

VREG

OFF

CAN

CK2

CAN

PAR

ADC

MUX

-

RWRWRWRW

Table 8.

XMISC register: ADCMUX bit

Bit

Function

ADCMUX

ADC Multiplexer

0: Default configuration, analog inputs on ports P5.y can be converted.

1: Analog inputs on port P1.z can be converted, only 8 channels can be

managed.