errata812D1, CD2
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a
MicroConverter
TM
, Multi-Channel 12-bit
ADC with Embedded FLASH MCU
Errata Sheet
ADuC812
A
. This Errata sheet represents the known bugs, anomalies and work-arounds for the ADuC812 MicroConverter.
B
. The Errata listed, apply to all ADuC812 packaged material branded as follows :
(Pre-Production Material)
(Production Material)
ADUC812XS
ADUC812BS
Date Stamp AD Logo
Date Stamp AD Logo
Lot Number
Lot Number
Where the Date Stamp number is less than 9933.
(
Enginnering Lot Exception
: Errata Listed in this sheet
do not
apply to parts branded with
Lot Number/Date Stamp combination = F104366.1 / 9925,
please refer to Errata Sheet RevE.0)
C
. Errata Sheets referring to later silicon revisions are available on our web-site at
D.
Because of silicon revisions and improved work-arounds, this Errata Sheet will be upgraded periodically. Please
find the latest Errata Sheet listed on the World Wide Web at :
E.
Analog Devices Inc. is committed, through future silicon revisions to continuously improve silicon functionality.
Analog Devices Inc. will use its best endeavors to ensure that these future silicon revisions remain compatible with
your present software/systems that implement the recommended work-arounds outlined in this document.
REV. D.1 Aug/99
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
â„¢ MicroConverter is a Trademark of Analog Devices, Inc.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
Analog Devices, Inc., 1998
 ADuC812
Errata Sheet
1. ADC FUNCTION - ADC CONVERSION IN DMA MODE :
Background:
The ADC can be triggered by 1 of 4 trigger events in Normal and DMA operating
modes, namely: Single Software Conversion, Continuous Software Conversions,
External Pin Triggered Conversions and Timer2 triggered Conversions. DMA mode
is initiated by setting the DMA bit in the ADCCON2 SFR and the DMA controller
proceeds starting from the external data memory address indicated by the DMA
address SFRs DMAL/H/P. Once a DMA conversion sequence is complete, both the
DMA bit and the bit controlling the conversion mode are reset by the DMA
controller.
Issue:
a. DMA operation will not execute when triggered from Timer2 driven conversions
unless DMA Address (DMAL/H/P) is initially set to 000000H.
b. The conversion mode bits (EXTC and T2C) are NOT reset upon completion of
a DMA conversion sequence triggered by Timer2 or external CONVST events.
c. A write to DMA address registers DMAL or DMAH can corrupt the LSB of the
adjacent DMA address register byte (DMAH or DMAP).
Work-Around :
a. For Timer2 triggered DMA conversions, ensure that the DMA start address is set to
000000H.
b. When using Timer2 or Ext. Pin triggered DMA conversions, ensure that you force
EXTC and T2C bits (ADCCON2) to reset by writing to these bits immediately after
DMA completion. This will ensure that the ADC halts conversion as soon as the DMA
sequence has completed.
c. The DMA address registers should be written in the following order: DML,
DMAH, DMAP.
Related Issues :
None.
2. ADC FUNCTION - TIME BETWEEN ADC CONVERSIONS
Background:
The ADC can be triggered by 1 of 4 trigger events in Normal and DMA
operating modes, namely: Single Software Conversion, Continuous
Software Conversions, External Pin Triggered Conversions and Timer2
triggered Conversions. In all modes of operation the ADC is specified for
12-bit INL and DNL performance.
Issue:
If an ADC conversion is initiated 100msecs or more after the last
conversion has taken place, the accuracy of this new conversion result
cannot be guaranteed.
Work-Around:
Ignore or repeat the first conversion if the time between this
conversion and the previous conversion is greater than 100msecs.
Related Issues:
None
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REV. D.1 Aug/99
Errata Sheet
ADuC812
3. UART FUNCTION - MULTIPROCESSOR COMMUNICATIONS MODE :
Background:
UART Modes 2 and 3 (programmed via SCON) have a special provision for
multiprocessor communications. In these modes, nine data bits are received and the
ninth bit goes into RB8. In this mode the port can be programmed so that when the
stop bit is received, the serial port interrupt is activated only if RB8(SCON) = 1.
This feature is enabled by setting the SM2 bit in SCON.
Issue:
With SM2 set, the serial port interrupt is set each time a stop bit is received,
regardless of the state of the RB8 bit.
Work-Around :
Implement a software polling scheme in the Serial Port ISR so that the state of the
RB8 bit is checked on entering the ISR. If RB8 is ‘0’ then a ‘RETI’ is executed to
exit the ISR immediately, and only if RB8 is set will the ISR function be executed.
Related Issues :
None.
4. SPI FUNCTION - OPERATION OF THE SPI INTERRUPT BIT ISPI :
Background:
The SPI Interrupt bit ISPI in the SPI Control SFR (SPICON) is set at the end of an
SPI transfer (8 SPI Clocks). Typically this bit can be used in an interrupt driven
routine to vector to the SPI Interrupt Vector Address at 003BH. Alternatively this bit
can be polled in software to detect a new reception or completion of a byte
transmission.
Issue:
In an interrupt driven routine this bit is automatically cleared when the PC vectors to
the SPI ISR. However, in a polled implementation the bit is not writable and is not
cleared on subsequent accesses to the SPI data SFRs. This means that in a software
polled scheme the ISPI bit is set after the first transmission but will not and cannot be
cleared for subsequent byte communications which can result in subsequent reads of
the same initial byte or corruption of a byte transmission before it is completed.
Work-Around A:
Use the SPI peripheral in interrupt driven mode only, thereby avoiding
any issues with the ISPI bit as this bit is automatically set and cleared in an SPI
interrupt driven routine.
Work-Around B:
In master mode SPI operation, use dummy ‘NOP’ instructions to time out a
complete SPI 8-Clock cycle before trying to access the SPI data SFRs.
Related Issues :
None.
5. SPI FUNCTION - SLAVE MODE FUNCTIONALITY :
Background:
In synchronous slave mode (CPOL=0/1, CPHA=0) the new MSB output value
appears on MISO when
SS
goes low.
Issue:
The SPI slave does not function correctly as a transmitter in modes 00 and 10 (i.e. when
CPHA=0). The MSB of the transmitted byte is corrupted by the MSB of the byte just
received.
Work-Around :
To transmit in Slave mode use the alternate SPI Slave operating mode (CPOL=0/1,
CPHA=1).
Related Issues :
None.
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REV. D.1 Aug/99
ADuC812
Errata Sheet
6. PORT 2 AND PORT 3.3 INTERNAL ACTIVE PULL-UP FUNCTIONALITY :
Background :
As with standard 8051 compatible Port functionality, Port 2 (P2.0 - P2.7)
and Port 3 (P3.0 - P3.7) digital I/O pins on the ADuC812 chip feature
internal pull-up resistors.
Issue :
All Port 2 pins and P3.3 on this revision of silicon are configured as open
drain when driven as digital outputs.
Work-Around :
External pull-up resistors must be used to pull up any Port 2 or P3.3 pin
being used as an digital output.
Related Issues :
Port 2 pins operate correctly (including internal pull-up resistors)
when operating as part of the external memory interface on the device.
7. FLASH/EE MEMORY - 3V PROGRAMMING :
Background :
The ADuC812 contains 2 separate arrays of Flash/EE memory, namely :
- 8 KBytes Internal Code Space .
- 640 Bytes Flash/EE Data Memory.
The 8 KBytes code space can be programmed in serial download
or parallel programming modes, while the 640 Byte data
space can be written by user software via a specified SFR interface.
Issue :
This revision of silicon does not support programming the 8K code or 640
Byte data Flash/EE memories at DV
DD
power supplies of less than 4.5V.
Work-Around :
The device should be programmed at DV
DD
=5V.
Related Issues :
None.
8. CODE EXECUTION - TRANSITION FROM INTERNAL TO EXTERNAL CODE SPACE :
Background :
As with standard 8051 microcontroller functionality the ADuC812 will
execute from internal code space when the
EA
pin is tied high. If the PC
rolls over the 8K internal code boundary or is vectored to a location
greater than 8K (using a jump instruction for example), the external
program memory interface is enabled so as to continue code execution in
the external code space.
Issue :
A transition from internal to external code will not function correctly.
Specifically the P0 outputs designating the low address byte during an
op-code fetch is not driven correctly during the first op-code byte fetch
cycle, resulting in incorrect or invalid op-code execution. This anomaly
will occur during a code rollover to external memory or a ‘jmp’ or ‘call’ to
a subroutine residing in external memory.
Work-Around :
User software should execute a ‘MOV P0,#00H’ instruction immediately
before a rollover, jump or call to external code space is executed to avoid
this anomaly.
Related Issues :
None.
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REV. D.1 Aug/99
ADuC812
Errata Sheet
9. FUNCTIONALITY OF PSMCON.1 BIT IN THE PSMCON SFR :
Background :
The PSMCON.1 bit in the PSMCON SFR can be used to indicate which supply
caused the active power supply trip condition. PSMCON.1=0 indicates a DV
DD
fault while PSMCON.1=1 indicates an AV
DD
fault.
Issue :
If the power supply trip point selection bits are set to select the 4.63V or 4.37V
supply trip points, the PSMCON.1 (AV
DD
/DV
DD
power supply trip indicator) bit
may not correctly indicate which supply has caused the fault. The supply trip
indicator bit will function correctly at all other trip point voltage levels.
Work-Around :
Pending.
Related Issues :
It should be noted that while the trip indicator bit function is suspect at these trip
levels, the PSM function itself is still 100% operational (even at 4.63V and 4.37V
trip levels) generating an interrupt as soon as any one of the supply pins falls below
the specified supply voltage trip point selection.
10. FLASH MEMORY - SECURITY BITS FUNCTIONALITY :
Background:
3 undocumented security bits exist at Page 160 (A0H) of User Flash/EE memory.
The security bits can be accessed in parallel programming mode and through the
SFR read/write interface to the User Flash/EE memory.
Issue:
The security bits do not function correctly. Do NOT program page 160 (A0H) of
User Flash/EE memory.
Work-Around :
Pending.
Related Issues :
None.
11. LOW TEMPERATURE RELATED ISSUES :
(FIXED ON CURRENT SILICON)
A. Internal Voltage Reference :
The on-chip V
REF
accuracy specification is 2.5V±50mV. This specification may
degrade on some parts operating at ambient temperatures below -20°C and AV
DD
/
DV
DD
greater than 5.0V. The V
REF
voltage output accuracy under these conditions
may degrade from 2.5V±50mV to typically 2.5V±100mV.
B. DAC Output :
The DAC voltage output on some parts may oscillate at ambient temperatures below
-20°C when operating at AV
DD
/DV
DD
greater than 5.0V.
12. XTAL1 LOGIC INPUT VOLTAGE :
The XTAL1 input is NOT included in the datasheet Input High Voltage
Specification. The input high voltage specification for this pin is specified
as 4.0V minimum.
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REV. D.1 Aug/99
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