QT60486-AS Atmel, QT60486-AS Datasheet - Page 7

• Manufacturer Part Number: QT60486-AS
• Description: SENSOR IC MTRX TOUCH48KEY 44TQFP
• Manufacturer: Atmel
• Series: QMatrix™, QProx™r
• Type: Capacitiver

Specifications of QT60486-AS

• Rohs Status: RoHS non-compliant
• Number Of Inputs/keys: 48 Key
• Resolution (bits): 9, 11 b
• Data Interface: Serial, SPI™, UART
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 25mA
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 44-TQFP, 44-VQFP
• Output Type: *
• Interface: *
• Input Type: *
• For Use With: 427-1088 - BOARD EVAL QT60486-AS QMATRIX

The MISO pin on the QT floats in 3-state mode between bytes
when /SS is high. This facilitates multiple devices on one SPI
bus.
Null Bytes: When the QT responds to a command with one
or more response bytes, the host can issue a new command
to the QT instead of a null in the last shift operation.
New commands attempted during intermediate byte transfers
are ignored, and null bytes should always be used in these
cases.
3.3 UART Communications
See also SR setup parameter, page 16.
UART mode is selected if the host sends data over the UART
lines first. There is no other configuration required to make
the device operate in UART mode. Once UART is selected
after a power-up, the device cannot switch to SPI mode
unless the device is reset.
UART mode communications functions in the same basic way
as SPI communications. The Baud rate is adjusted by means
of setup parameter ‘SR’ (pages 16, 0). Once a new Baud rate
has been set, the device must be reset for the new rate to
take effect.
The major difference with SPI mode is that the UART mode is
asynchronous and so the host does not clock the QT. No
framing /SS or clock signal is required, simplifying the
interface greatly. Return data is sent from the QT back to the
host when the data is ready.
Multi-drop capability: The QT60xx6 in UART mode floats Tx
within 10µs after each transmitted byte. The host’s Rx pin can
thus be shared with other similar UART based peripherals.
Wake operation: The device can be put into sleep mode with
a serial command, 0x16 (page 9) and then be waked with a
dummy null byte from the host, if the Rx and WS pins are
connected together.
Rx - Receive async data. This pin is an input only.
Tx - Transmit async data. Drives out when transmitting but
lQ
Advanced information; subject to change
floats within 10
µ
s of the end of the stop bit, to allow
7
UART transmission parameters are:
DRDY in UART mode: Section 3.1 applies.
DRDY is bi-directional in UART mode. DRDY can be pulled
down by either the QT or the host (wire-AND), so that either
device can be inhibited from sending data until the other is
ready. The host should obey this control line or transmission
errors can occur. The host should grant a 10µs grace period
after clamping DRDY low in which it can still accept a
transmission.
As explained in Section 3.1, DRDY is not clamped low
immediately after the QT receives a byte; there can be up to a
100µs delay from the end of the stop bit before DRDY goes
low. Sampling of DRDY by the host should occur 100µs after
the byte has been fully sent; if DRDY is already high at this
point, or becomes high, then it is clear to send.
Null Bytes: Unlike SPI mode, there is no reason to send null
bytes to the QT in UART mode.
bussing with several similar parts. Tx should idle high, and
must be pulled high with a 10K ~ 20K resistor to Vdd at all
times in UART mode. Tx is push-pull when transmitting
data.
Baud rate:
Start bits:
Data bits:
Parity:
Stop bits:
Figure 3-3 UART Connections
Host MCU
P_IN
Rx
Tx
10K
10K
Vdd
Vdd
9600 ~ 115,200
1
8
None
1
QT60486-AS 0.07/1103
QT60xx6
DRDY
Rx
Tx