CapSense Schematic Design
AN66308 - CY8CMBR2044 CapSense® Design Guide, Doc. No. 001-66308 Rev. *F
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Table 3-4. Resistor Value Selection for Button Scan Rate
Button Scan Rate varies from device to device. It is ±12 percent accurate at room temperature and ±18 percent
accurate at a temperature range of -
–40 °C to +85 °C.
Sleep Mode
There are two possible configurations:
1. Connect the Button Scan Rate resistor to ground. This enables low power sleep mode
2. Connect the Button Scan Rate resistor to an external Master (host processor) and configure the host pin to be
HIGH (V
DD
). This enables deep sleep mode.
Serial Debug Data Out
Serial Debug Data reports firmware revision, CapSense status, GPO status, raw count, baseline, difference count,
and parasitic capacitance for all buttons. When Serial Debug Data is enabled this information is output on a single
CSx pin. To enable Serial Data Out, pull down the CSx pin where you want the serial data to appear with a 5.6-
kΩ
resistor with a 5-percent tolerance. If more than one CSx pin is pulled down, debug data is sent out only on one CSx
pin. The priority is:
CS0 > CS1 > CS2 > CS3
The Cypress
can be used to view the data. The Serial Debug Data is sent by the device in the order
according to Table 3-5. The MultiChart tool arranges the data in the format as shown in
Table 3-6
.
Serial data is sent out with ~115,200 baud rate.
For designs using less than four CapSense buttons, the unused CS pin should be selected for Serial Debug Data.
For designs using all four CapSense buttons, use two CSx pins for Serial Debug Data. For example, pull down CS0
with a 5.6-
kΩ resistor and read the data for CS1, CS2, and CS3. Next, pull down CS1 with a 5.6-kΩ resistor and read
the data for CS0, CS2, and CS3.
