sx8675iwltrt Semtech Corporation, sx8675iwltrt Datasheet - Page 20

• Manufacturer Part Number: sx8675iwltrt
• Description: Haptics Enabled Multitouch 4/5-wire Resistive Touchscreen Controller With Proximity Sensing
• Manufacturer: Semtech Corporation

ADVANCED COMMUNICATIONS & SENSING
When a command is received, the chip executes the associated tasks listed in table below and waits for the next
command. It is up to the host to sequence all actions.
Pen detection is performed after each CONVERT command and if pen is not detected, no touch operation is
performed. Following figures assume pen down. PENSTAT is not updated in MAN mode.
To enter MAN mode the host must send the MAN command and then set TOUCHRATE = 0.
As illustrated in figure below the CONVERT command will bias the channel, wait for the programmed settling
time (POWDLY), and run the conversion.
When the CONVERT command is used with CHAN=SEQ, multiple channels as defined in RegChnMsk are
sampled. In this case, each channel will be sequentially biased during POWDLY before a conversion is started.
At the end of each channel conversion the bias is automatically removed.
In case the range of POWDLY settings available is not enough to cover the required settling time, one can use
the SELECT command first to bias the channel, and then send the CONVERT command hence extending bias
time. SELECT command cannot be used with CHAN=SEQ.
Rev 1 – 25
Figure 21 – Manual Mode – CONVERT Command (CHAN = SEQ = [X;Y]; PROXSCANPERIOD = 0)
Channel Conversion
Channel Conversion
Channel Conversion
CONVSTAT
NIRQ (RegIrqMsk[3]=1)
Channel Bias
CONVSTAT
NIRQ (RegIrqMsk[3]=1)
Channel Bias
CONVSTAT
NIRQ (RegIrqMsk[3]=1)
Channel Bias
I2C
I2C
I2C
th
Figure 20 – Manual Mode – CONVERT Command (CHAN = Y; PROXSCANPERIOD = 0)
Command
CONVERT(CHAN)
SELECT(CHAN)
July 2011
SELECT(Y)
CONVERT(SEQ)
Table 7 – Manual Mode Commands
Actions
Select and bias CHAN
Wait for the programmed settling time (POWDLY)
Convert CHAN
Select and bias CHAN
Actual bias time
Resistive Touchscreen Controller with Proximity Sensing
CONVERT(Y)
CONVERT(Y)
POWDLY
20
Y
X
X
POWDLY
POWDLY
POWDLY
SX8674/SX8675/SX8676
Y
Y
Y
Y
Y
Haptics Enabled Multitouch 4/5-Wire
READ CHANNEL
READ CHANNEL
READ CHANNEL
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