In SPI communications, when the QT60xx6 responds to a
command with one or more response bytes, the host can issue
a new command instead of a null on the last byte shift
operation.
The host can monitor the progress of the recalibration by
checking the status byte, using command 0x05, during the
course of the calibration.
A key will show an error flag (using command 0x8k) indicating
the key has failed calibration if its signal is too noisy or if its
signal is below the low signal threshold. A key is deemed too
noisy if, at the end of calibration, the signal is no longer
between its computed negative hysteresis level and positive
thresholds.
New commands during intermediate byte shift-out operations
are ignored, and null bytes should always be used.
4.2 Enter Setups Mode - 0x01
This command is used to initiate the Setups block transfer from
Host to QT.
4.4 Force Reset - 0x04
The command must be repeated 2x within 100ms or the
command will fail; the repeating command must be sequential
without any intervening command. After the 2nd 0x01 from the
host, the QT will stop scanning keys and reply with the
character 0xFE. In SPI mode this character must be shifted out
by sending a null (0x00) from the host. This command
suspends normal sensing starting from the receipt of the
second 0x01. A failure of the command will cause a timeout.
The command must be repeated 2x within 100ms or the
command will fail; the repeating command must be sequential
without any intervening command. After the 2nd 0x04, the
device will reply with the character 0xFB just prior to executing
the reset operation.
After any reset, the device automatically performs a full key
calibration on all keys.
Each byte in the block must arrive at the QT no later than
100ms after the previous one or a timeout will occur. Any
timeout will cause the device to cancel the block load and go
back to normal operation.
The host can monitor the progress of the reset to see when the
chip is operating again by checking the status byte for
recalibration, by repeatedly issuing command 0x05 (see below).
If no response comes back, the command was not received and
the device should preferably be reset by the host just in case
there are any other problems.
4.5 General Status - 0x05
This command returns the general status bits. This command is
not as useful as the 0x06 command for routine use. The bits
returned from 0x05 are as follows:
If 0xFE is received by the host from the QT, then the host
should begin to transmit the block of Setups to the QT. The
DRDY line handshakes the data. The delay between bytes can
be as short as 10µs but the host can make it longer than this if
required, but no more than 100ms. The last two bytes the host
should send is the CRC for the block of data only (ie the CRC
should not include the command in its calculation).
BIT
7
Description
Reserved
6
1= communications failure
1= FMEA failure detected
1= eeprom corrupt
1= Mains sync error
1= calibration has failed on an
enabled key or, an LSL failure
1= any key in calibration
1= any key in detect
5
4
3
After the block transfer the QT will check the CRC and respond
with 0x00 if there was an error. Regardless, it will program the
internal eeprom. If the CRC was correct it will reply with a
second 0xFE after the eeprom was programmed.
2
1
0
If there was an error in the block transfer the device will restore
the last known good Setups from Flash memory the next time
the device is reset. However until that point, the device will
attempt to operate using the new Setups block even if it is
corrupt. Note that some Setups do not take effect until the part
is reset (e.g. Baud rate).
Notes:
Bit 6: Set if a communications failure. This can be reset by
sending command 0x0f (“last command command”) repeatedly
until a response of 0xf0 is received.
Bit 5: Set if an FMEA error was detected during operation. See
Section 2.16. A further amplification of what the FMEA error
consisted of is described in Section 4.12.
At the end of the full block load sequence, the device restarts
sensing without recalibration. Most of the setups in the block
will take effect immediately, but it is important to reset the
device after a block load to make all the changes effective
and permanent. See Section 4.4.
Bit 4: Set if eeprom corruption was detected. If this happens, it
is recommended that the device be reset. If a reset does not
cure the problem, the Setups block should be reloaded (Section
4.2) and the device reset again.
Command response timing: Responses to the bytes in the
setups block (both DRDY and return byte at the end) by the
part can take as long as 20ms each.
Bit 3: Set if there was a mains sync error, for example there
was no Sync signal detected within the allotted 100ms amount
of time. See Section 5.12. This condition is not necessarily fatal
to operation, however the device will operate very slowly and
may suffer from noise problems if the sync feature was required
for noise reasons.
4.3 Cal All - 0x03
This command must be repeated 2x within 100ms or the
command will fail; the repeating command must be sequential
without any intervening command.
Bit 2: Reports either a cal failure (failed in 5 sequential
attempts) on any enabled key or, that an enabled key has a
very low signal reference value, lower than the user-settable
LSL value (Section 5.15).
After the 2nd 0x03 from the host, the QT will reply with the
character 0xFC. Shortly thereafter the device will recalibrate all
keys and restart operation.
Bit 1: Set if any key is in the process of calibrating.
Bit 0: Set if any key is in detection (touched).
If no 0xFC comes back, the command was not properly
received and the device should preferably be reset.
lQ
14
QT60486-AS R8.01/0105
QUANTUM [ QUANTUM RESEARCH GROUP ]
