STATUS SHEET
Status Sheet – TCM 320 DA Page 1/2
STATUS SHEET
Type: TCM 320
Step Code: DA
Date: 08. April 2010
Product Status
Series production
Customer Documentation
TCM3xx User Manual V1.00
TCM3xy Data Sheet March 2010
Dolphin Core Description V0.80
EO3000I_API_V2.0.0.0 (API Manual)
Spec Restrictions
DAC: small offs et, inaccuracy at small values, not unif ormly continuous
VDD current peak of several 100mA for 2-4 µs after powerup/wakeup
Errata and Workarounds
Malfunction of internal pull-downs at PROG_EN and RESET
Description:
Under certain circumstances it can happen that the internal pull-downs at PROG_EN
and RESET are not working properly. In case the pull-down at PROG_EN does not work
it can happen, e.g. under bad EMI or temperature conditions, that at start-up of the
module the bootloader jumps into programming mode instead of operating mode. The
module then hangs in programming mode and a reset or new start-up is required.
A malfunction of the pull-down at RESET pin can lead to an unwanted reset of the
module.
Workaround:
Please connect an external 10kΩ pull-down resistor to these pins!
STATUS SHEET
Status Sheet – TCM 320 DA Page 2/2
UART hangs up (transmitting) or looses bytes (receiving) during full duplex
operation
Description
Under certain circumstances it is possible that an UART transmi t or receive interrupt is lost. This
only happens during full duplex (simultaneous transmitting and receiving) serial operatio n.
The transmit and receive interrupt flags are bit-addressable in the 8051 S FR (special function
register) space and are located i n the same 8 bit register. From software perspective clearing of
an interrupt flag is an atomic operation, but on the hardware side, a read-modify-write occurs
(since the register is a single 8-bit unit). The problem now occurs when a new transmit/recei ve
interrupt occurs (respective interrupt flag is set) between the read and write cycl es.
There are two possible scenarios resulting in two different effects:
1. During clearing of a receive interrupt flag the transmit interrupt flag is set (TI occurs within 2
clock cycles after an RI=0 instruction). Then the transmit interrupt flag is accidental cleared and
transmitting of further bytes will hangs up.
2. During clearing of a transmit interrupt flag the receive interrupt flag is set (RI occurs within 2
clock cycles after an TI=0 instruction). Then the receive interrupt flag is accidental cleared and
the received byte will be lost.
Workaround
1. Use half duplex communication
If possible use half duplex communication. This will completely avoid the behaviour described
above.
2. Avoid hanging up of transmitting bytes by adding a timeout mechanism
The Dolphin API (>= V1.4.0.0) has implemented a timeout mechanism usin g the system sched-
uler (timer interrupt). With every 1 ms tick the scheduler proves if UART transmission is ongoing
and whether the communication was locked or not. If it was locked the scheduler unlocks this
manually and the error log counter ERR_UART_TX_INT_LOST is incremented.
This will result in an inter-byte delay between 1 ms (best case) and 4 ms (worst case) of the
transmitted bytes.
If the Application is using the API System log feature, it is possible to detect this unlock events
(for more info read EO3000I_API.chm->Error Diagnostic->System Log).
Note:
This API workaround does not apply to ultra low power applications where the scheduler
is not running!
3. Handling of lost received bytes
There is no workaround completely avoiding loosing a received byte.
The Dolphin API (>= V1.4.0.0) has implemented a mechanism where a newly received byte is
also detected under the error condition if the new byte has a different value than the previous
one (does not work if the bytes are identical). In such case the ERR_UART_RX_INT_LOST i s
incremented.
If the Application is using the API System log feature, it is possible to detect this rescue events
(for more info read EO3000I_API.chm->Error Diagnostic->System Log).
Additionally usi n g of a protocol, e.g. ESP2 (using the Serial Telegram Checksum) or ESP3 (using
the Packet CRC8), allows to detect lost bytes and to request and resend the data.
