aduc7030 Analog Devices, Inc., aduc7030 Datasheet - Page 130

• Manufacturer Part Number: aduc7030
• Description: Integrated Precision Battery Sensor For Automotive
• Manufacturer: Analog Devices, Inc.

ADuC7030/ADuC7033
Serial Test Interface Output Structure
The Serial Test Interface is a high voltage output, which
incorporates a low side driver, short circuit protection and
diagnostic pin read-back capability. The output driver circuit
configuration is shown in Figure 40 below.
Using the Serial Test Interface
Data will only begin transmission once configuration of the STI
port has been completed in the following sequence:
a.
b.
c.
Timer 4 is configured with the correct load value to generate an
overflow at the required baud rate. If the STI port is being used
to transmit ADC conversion results, then the baud rate must be
Configure Timer4 for baud rate generation
Correctly enable STICON using STIKEY0 and STIKEY1
for secure access
Required bytes to be transmitted are written into
STIDAT0, STIDAT1 and STIDAT2.
READ-BACK
GP2CON[24]
TRANSMIT
HVSTA[7]
PIN
STI
Figure 40. STI Output Structure
PROTECTION CONTROL
SHORT CIRCUIT
HVCFG1[2]
REF1
STI
Rev. PrE | Page 130 of 150
sufficient to output each ADC result (16-bits) prior to next
ADC conversion result being available.
For example, if the ADC is sampling at 1kHz, then the baud rate
has to be sufficient to output 36 bits, 3 x 8 bits (16-bit ADC
result and a checksum byte for example) + 3 x 1 Start bits + 3 x
1 Parity bits + 3 x 2Stop Bits = 36 bits. Therefore, the Serial Test
Interface must transmit data at greater than 36kbps. The closest
standard baud rate is 38.4kbps.
Therefore the reload value written to the Timer4 load MMR
(T4LD) is 0106h(267d). This value is calculated as shown below
and is based on a pre-scalar of 1, using a core clock of
10.24MHz.
Once the Timer4 load value is written and the Timer itself is
configured and enabled using the T4CON MMR, the STI port
must be configured. The is done by writing to the STICON
MMR in a specific sequence using the STIKEY0 and STIKEY1
MMRs as described earlier.
Finally, the STI port will not begin transmission until the
required number of transmit bytes is written into the STIDATx
MMRs. As soon as STI starts transmitting, the value in the
STICON MMR will change from the value initially written to
this register. User code can ensure that all data is transmitted by
continuously polling the STICON MMR until it reverts back to
the value originally written to it. To disable the serial interface,
user code must write a 0 to STICON[0].
T 4
LD
= 10.24MHz/ 38.4kbps = 267
CoreClockF
DesiredBau
Preliminary Technical Data
requency
dRate