In this post, I will take you through the PRoC BLE schematic and firmware.  I describe a very similar version to this in great detail in the video you can find on the Cypress Video Training website.

First, I create a new project in my workspace called “145capsenseled-ble.”  Then, I add the UART component (the SCB version) and the BLE component.


Next, I configure the component to be a GATT server with a custom profile and a GAP client.


Then I create a custom service with two characteristics:

  • The “led” characteristic, which is set up as a uint8 that is writeable and readable.
  • The “capsense” characteristic, which is set up as uint16 that is readable and has a “notify.”

Next, I configure the UUIDs of the service and characteristics to match what is hard-coded in the iOS app.  Then, I add “Client User Descriptions” that describe the characteristics in plain text.


Next I configure the GAP settings, specifically the advertising packet.


I make the pin I assignments, which is just the UART Rx and Tx lines.


Finally, I write the firmware.  I started with main.  In the infinite loop (line 116), if I have received a byte from other side, then I assign it to the global variable “fingerPos” (line 118). Next, call updateCapsense() (line 119), to update the GATT database with the new value of the slider.


The updateCapsense function:

Lines 31/32 If there is no connection, then don’t update the GATT database.

Lines 33-39 Update the GATT database with the current fingerPosition.

Lines 42-43 If the iPhone side has asked for notification and the position has changed, then send a notification.

Line 44 Save the last position.


The BleCallBack is the most complicated section of firmware.  It uses a “switch” statement to handle the different event “cases.” The cases are:

  • CYBLE_EVT_STACK_ON & CYBLE_EVT_GAP_DEVICE_DISCONNECTED:  In either of these cases you want to start the advertising function.
  • CYBLE_EVT_GATT_CONNECT_IND: When there is a connection made, update the GATT database with the current state of the CapSense and the LED.  This allows the iOS side to read the correct values.
  • CYBLE_EVT_WRITE_REQ: There are two kinds of write requests that are valid.
    • CYBLE_LED_CAPSENSE_LED_CHAR_HANDLE:  If the remote side writes into the LED value, then send that data to the PSoC4000S via the UART.
    • CYBLE_LEDCAPSENSE_CAPSENSE_CAPSENSECCCD: If the remote side has been asked to notify (or un-notify), then save that in the global variable capsenseNotify.


That is all of the firmware.

In the next post, I’ll take you through the debugging I had to do.

You can find the PSoC Creator workspace on github in the directory called “capsenseble-145.”

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