ST10R272L-B0 STMICROELECTRONICS [STMicroelectronics], ST10R272L-B0 Datasheet - Page 2

• Manufacturer Part Number: ST10R272L-B0
• Description: 16-BIT ROMLESS LOW VOLTAGE MCU WITH MAC
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST10R272L-B0 Errata Sheet
2.2 ST_MAC.9: COCMP INSTRUCTION INVERTED OPERANDS
According to the ST10 Family Programming Manual, the CoCmp instruction substracts a
40-bit signed operand from the 40-bit accumulator content (acc - op2\op1), and updates the
N, Z and C flags in the MSW register, leaving the accumulator unchanged.
In error, the reverse operation (op2\op1 - acc) has been implemented in the MacUnit. There-
fore, the N and C flags are set according to the reverse operation (Z flag is not affected).
Workaround: Change interpretation of the N and C flags in the MSW register.
2.3 ST_MAC.10: E-FLAG EVALUATION FOR COSHR AND COASHR INSTRUCTIONS
WHEN SATURATION MODE IS ENABLED
The Logical and the Arithmetic Right Shift instructions (CoShr/CoAshr) are specified not to be affected
by the saturation mode (MS bit of the MCW reg.). The result loaded in the accumulator is never saturat-
ed but the evaluation of E flag in the MSW register is erroneous when saturation mode is enabled
and the E flag would be set
In this example, the E flag is kept clear however MAE is used.
Workaround: Disable saturation mode before using Logical and Arithmetic Right Shift in-
structions and re-enable it just after.
2/4
MS bit is set: saturation
mode is enabled
Example:
Mov
CoLoad
Nop
Mov
Nop
CoShr
.
R5,
#5555h
R5, R5
MSW,
#007Fh
#1
Accumulator
--
00
00
7F
7F
3F
----
5555
5555
5555
5555
AAAA
----h
5555h
5555h
5555h
5555h
AAAAh
SL
-
0
0
0
0
0
error
E
-
0
0
0
0
0
SV
-
0
0
0
0
0
C
-
0
0
0
0
0
Z
-
0
0
0
0
0
N
-
0
0
0
0
0