Tuner communication setup

The "Tuner Communication Setup" dialog is used to establish communication between the Tuner and target device. The Tuner supports I2C, UART, and RTT communication interfaces.

Select

Tools > Tuner Communication Setup…

on the menu to open the dialog or click the

Tuner Communication Setup

button. The dialog opens automatically after clicking the

Connect

button if no device was previously selected.

Select the device and communication interface by checking the item with the interface name. Change the interface configuration parameters to match the configuration of the communication peripheral in the application.

Note:

The parameters in the "Tuner Communication Setup" dialog must be identical to the parameters of the EZI2C or UART driver in the application.

I2C

To establish the

I2C

communication between the Tuner and target device, configure the Tuner communication parameters to match the parameters of the device EzI2C settings.

• The I2C communication can work in the two Read modes (see

  Main toolbar

  ).

UART

To establish the UART communication between the Tuner and target device, configure the Tuner communication parameters to match the parameters of the device UART settings.

Depending on the application capabilities, the UART communication may work in two modes: Read/Write and Read Only (see

Status bar

).

Note:

Recommended – enable the UART Flow control on the target device for bitrates equal or higher than 1000000.

RTT

The RTT is an interface specified by SEGGER based on basic memory reads and writes to transfer data bidirectionally between the target and host. Before configuring the RTT setup dialog, it is recommended to familiarize yourself with the RTT protocol fundamentals at

https://wiki.segger.com/RTT

.

The data transfer between the host and target devices is organized through channels. The Tuner communicates to the server (OpenOCD) via the TCP/IP protocol. The server in turn uses the SWD interface to communicate with the device.

RTT communication advantages:

• SWD pins are used instead of reserving EZI2C or UART pins.

• The communication speed is the highest among all options.

To establish the RTT communication between the Tuner and target device, start either the local RTT server or connect to an existing one. For details on the application layer, refer to

Setting up RTT communication in the application

.

Start RTT server locally

To start the RTT server in your local environment, select

Start RTT server locally

and modify the following fields:

• Executable

  – The

  • .elf

  file generated by the firmware build. In most cases, it will be prefilled automatically based on the ModusToolbox™ project.

• TCP ports range

  – Used for the RTT communication. Each port is mapped to a channel. Set up at least two channels because Channel 0 has limitations.

• Tuner TCP port

  – The TCP port used by the Tuner.

• OpenOCD .cfg file

  – Provides the * .cfg file name for OpenOCD. In most cases, it will be detected automatically based on the application target device and will not display on the GUI. If becomes visible when the * .cfg file name value cannot be detected by the Tuner automatically and must be selected manually. The * .cfg file name can be found in the .launch file of your project.

To manage the RTT server, the Tuner uses the *.rtt.tcl file located with the Tuner executable (or capsense-tuner.app/Contents/Resources/on macOS). It starts an OpenOCD session, which lasts while the Tuner is connected to the device.

Note:

Only one instance of OpenOCD can run at a time. If you want to debug the application simultaneously, refer to

RTT communication with simultaneous debug

.

Connect to an existing RTT server

To connect to an existing RTT server, deselect

Start RTT server locally

and modify the following fields.

• Hostname or IP

  – Specifies the host or IP address of the running RTT server.

• Tuner TCP port

  – The TCP port used by the Tuner.

Setting up RTT communication in the application

To enable the RTT communication, include the SEGGER RTT library in the application. It is a part of the J-Link Software and Documentation Pack, which is available for download on the

SEGGER official website

. The RTT library is located inside the "Samples" folder. Place it in the project root folder. Refer to the

RTT API documentation

to learn how to use it.

Add sample code to the

main.c

file:

• Include a header

  #include "SEGGER_RTT/RTT/SEGGER_RTT.h"

• Initialize RTT

  SEGGER_RTT_Init();

• Configure the up and down buffers.

  • Set the size of the up buffer to at least sizeof(cy_capsense_tuner) + 5 + 1 (5 bytes for the packet header and trailer, 1 byte for internal RTT purposes).

  • Set the size of the down buffer to at least 32 bytes.

  SEGGER_RTT_ConfigUpBuffer(RTT_TUNER_CHANNEL, "tuner", &tunerUpBuf, sizeof(tunerUpBuf), 
  SEGGER_RTT_MODE_NO_BLOCK_SKIP); 
  SEGGER_RTT_ConfigDownBuffer(RTT_TUNER_CHANNEL, "tuner", &tunerDownBuf, sizeof(tunerDownBuf), 
  SEGGER_RTT_MODE_BLOCK_IF_FIFO_FULL);

• Implement the send and receive functions. Assign them to the callbacks.

Static void rtt_tuner_send(void * context);
static void rtt_tuner_receive(uint8_t ** packet, uint8_t ** tunerPacket, void * context);
...
cy_capsense_context.ptrInternalContext->ptrTunerSendCallback    = rtt_tuner_send;
cy_capsense_context.ptrInternalContext->ptrTunerReceiveCallback = rtt_tuner_receive;
...
cy_capsense_context.ptrInternalContext->ptrTunerSendCallback    = rtt_tuner_send;
cy_capsense_context.ptrInternalContext->ptrTunerReceiveCallback = rtt_tuner_receive;

...

void rtt_tuner_send(void * context)
{
    (void)context;
    /* Packet size including 2-byte header and 3-byte trailer */
    uint16_t elemCount = sizeof(cy_capsense_tuner) + 5;

    /* Lock RTT */
    SEGGER_RTT_LOCK();
    SEGGER_RTT_BUFFER_UP *buffer = _SEGGER_RTT.aUp + RTT_TUNER_CHANNEL;
    /* Copy CAPSENSE tuner structure data to the buffer */
    ...
    /* Manually update the pointers */
    buffer->RdOff = 0;
    buffer->WrOff = elemCount;

    /* Unlock RTT */
    SEGGER_RTT_UNLOCK();
}

...

void rtt_tuner_receive(uint8_t ** packet, uint8_t ** tunerPacket, void * context)
{
    while(0 != SEGGER_RTT_HasData(RTT_TUNER_CHANNEL))
    {
        uint8_t byte;
        SEGGER_RTT_Read(RTT_TUNER_CHANNEL, &byte, 1);
        ...
    }
}

The Tuner is expected to receive packets in the following format:

OD 0A <cy_capsense_tuner> 00 FF FF

OpenOCD Log pane

The Tuner offers a special OpenOCD Log view to observe OpenOCD communication logs.

RTT communication with simultaneous debug

The RTT interface allows communication with the CAPSENSE™ Tuner and debugging simultaneously over the same pair of SWD pins. The RTT communication utilizes OpenOCD. To debug simultaneously, establish a connection with the Tuner and then attach the debugger to the already running OpenOCD session. For details, refer to the debug section of your IDE user guide.

Communication and Low power mode

The Tuner requires a working communication channel (I2C, UART, RTT). While the device is operating in Low power mode, it cannot communicate with the Tuner. In order to have a stable communication, Synchronization mode was introduced between the Tuner and the device. In this mode, the Tuner controls the device, particularly the moment of starting a next scan. If this process is interrupted, communication may be lost. To avoid this, follow the recommendations:

These are the limitations necessary for maintaining the successful connection of the Tuner with a device:

• The PSOC™ side firmware ensures that after the device exits Deep Sleep mode, the device stays in the active state with the working communication channel, which enables the Tuner to receive at least one packet with valid data.

• The device sleeps less than the Tuner-defined timeout (see the LP command timeout in the Tuner Configuration Options dialog,

  Advanced

  tab).

• Implement the Deep Sleep callback, which waits for the completion of an EzI2C/UART transaction before the transition to Deep Sleep.

Also recommended:

• Add

  Cy_SysLib_Delay

  100-500 ms after the CAPSENSE™ initialization completes before the transition to Deep Sleep to give the Tuner time to exchange packets with the device.

The Tuner has the following timeouts by default:

• Connect timeout: 3 sec

• Read/write timeout: 250 sec.

Status bar

The

Status bar

at the bottom of the GUI displays information related to the communication state between the Tuner and the device. Some sections differ depending on the communication type as follows:

I2C interface

UART interface

RTT interface

Fields

• Scan rate

  – A number of scans performed by the device per second.

• Packet rate

  – A number of read samples performed by the Tuner per second. The count depends on multiple factors: the selected communication channel, communication speed, and amount of time for a single scan. The Packet rate can be lower or equal to the Scan rate.

• Bridge status

  – Either Connected, when the communication channel is active, or Disconnected otherwise.

• Slave address

  (I2C) – The address of the I2C slave configured for the current communication channel.

• I2C clock

  (I2C) – The data rate used by the I2C communication channel.

• Mode

  – The data transmission mode:

  • Read/Write – Provides data transmission in two reverse directions: target device → Tuner→ target device. You can change the parameters of the widgets/sensors at run-time. To upload the modified configuration, click the

    Apply to Device

    button.

  • Read only – Provides data transmission in one direction: target device → Tuner. You cannot upload the parameters of the widgets/sensors to the device at run-time. But for the I2C protocol you can still upload parameters that do not require re-initialization.

• Baud rate

  (UART) – The data rate, at which CAPSENSE™ operates with the current settings.

• Tuner TCP port

  (RTT) – Used by the Tuner to connect to the RTT server.

• RTT Server

  (RTT) – Indicates if the RTT server is started locally or on a specific host.

• Supply voltage

  – The supply voltage.

• Logging

  – Either ON (when the data logging to a file in progress) or OFF.