The directory goal_media contains:

• media adapters: generic driver interfaces

• media interfaces: generic interfaces between media adapters and higher layers

One source and one header files exist for each GOAL media module. Only the sources for the necessary GOAL media modules shall be integrated in the compiler-project of the GOAL system. The registration is described in Chapter: Platform API. The functions are described in detail in the GOAL Reference Manual.
Figure 21 demonstrates the easy exchange of drivers.

Nonvolatile storage

GOAL provides a media adapter and media interface for the nonvolatile storage usable for program downloads and uploads by a bootloader or for the nonvolatile storage of configuration data. The nonvolatile storage media allows:

• to write data to the nonvolatile memory,

• to read data from the nonvolatile memory and

• to erase the nonvolatile memory.

NVS media interface

The media adapter is registered to the media interface by function goal_miNvsReg(). The resource "NVS media interface" must be allocated by function goal_miNvsAlloc(). The media interface is freed by function goal_miNvsFree().
The media interface allows to manage single memory ranges, called regions. Therewith it is possible to assign different memory ranges to various processes and to control the access to the nonvolatile memory process-specific. Each region is identified by an ID, called MI-NVS-REGION-ID, unique. This ID can be specified application-specific. But each ID must only exist once. During registration a unique handle is created for each MI-NVS-REGION-ID. Each region has to be registered to the media interface for nonvolatile storage by higher layers in the state GOAL_FSA_INIT. A region has the following properties:

Table: properties of NVS regions

Implementation guidelines

Registration of a memory region

1. Specify a region and define a MI-NVS-REGION-ID:
   
   

   #define GOAL_ID_MI_NVS_REGION_CONFIG_DATA 2

    

2. Create a MA-handle:
   
   

   GOAL_MA_NVS_T *pMaNvs;

    

3. Select the suitable NVS driver and initialize the driver. The driver registers to the media adapter by itself.

4. Create a MI-handle:
   
   

   GOAL_MI_NVS_T *pMiNvsHdl;

    

5. Register the media interface:
   
   

   goal_miNvsReg(&pMiNvsHdl);

    

6. Allocate the NVS service:
   
   

   goal_miNvsAlloc(pMiNvsHdl);

    

7. Create a MI-NVS-REGION-handle:
   
   

   GOAL_MI_NVS_REGION_T *pRegion;

    

8. Register and configure the memory region: The memory range starts at address 0x0001FFF and has a length of 0x100 byte. The region shall complete. Configurtion data shall be read and written.
   
   

   goal_miNvsRegRegion(&pRegion, pMiNvsHdl, pMaNvsHdl, 0x0001FFF, 0x00000100, "config data",GOAL_ID_MI_NVS_REGION_CONFIG_DATA); /* set mode */ goal_miNvsSetMode(pRegion, GOAL_MI_NVS_REGION_MODE_COMPLETE); /* set access rights */ goal_miNvsSetAccess(pRegion, GOAL_MI_NVS_REGION_ACCESS_WRITE);

Write data to nonvolatile memory

1. Load MI-NVS-REGION-handle of the memory region with the ID GOAL_ID_MI_NVS_REGION_CONFIG_DATA:
   
   

   GOAL_MI_NVS_REGION_T *pRegion; goal_miNvsRegionGetById(&pRegion, GOAL_ID_MI_NVS_REGION_CONFIG_DATA);

    

2. Erase the nonvolatile memory region:
   
   

   goal_miNvsErase(pRegion);

    

3. Write data of size bytes to nonvolatile memory region:
   
   

   goal_miNvsWrite(pRegion, (uint8_t *)pData,0, size);

Read data from nonvolatile memory

1. Load MI-NVS-REGION-handle of the memory region with the ID GOAL_ID_MI_NVS_REGION_CONFIG_DATA:
   
   

   GOAL_MI_NVS_REGION_T *pRegion; goal_miNvsRegionGetById(&pRegion, GOAL_ID_MI_NVS_REGION_CONFIG_DATA);

    

2. Read data from nonvolatile memory:
   
   

   goal_miNvsRead(&pRegion, (uint8_t *)pData, 0, size);

NVS media adapter

The selected NVS driver registers itself to the NVS media adapter.

Implementation guidelines

These implementation guidelines refer to the case, that no NVS media interface is used.

Write data to nonvolatile memory

1. Create a MA-handle:
   
   

   GOAL_MA_NVS_T *pMaNvsHdl;

    

2. Select the suitable NVS driver and initialize the driver. The driver registers to the media adapter by itself.

3. Create a NVS description:
   
   

   GOAL_MA_NVS_DESC_T desc = { .strName = „config data", .fCompleteAccess = GOAL_TRUE}

    

4. Erase 0x100 bytes in the nonvolatile memory from start address 0x0001FFF:
   
   

   goal_maNvsErase(pMaNvsHdl, &desc, 0x0001FFF, 0x100);

    

5. Write 0x100 bytes from the buffer pData to the nonvolatile memory on start address 0x0001FFF:
   
   

   goal_maNvsWrite(pMaNvsHdl, &desc, 0x0001FFF, (uint8_t *)pData, 0x100);

Read data from nonvolatile memory

1. Create a MA-handle:
   
   

   GOAL_MA_NVS_T *pMaNvsHdl;

    

2. Select the suitable NVS driver and initialize the driver. The driver registers to the media adapter by itself.

3. Create a NVS description:
   
   

   GOAL_MA_NVS_DESC_T desc = { .strName = „config data", .fCompleteAccess = GOAL_TRUE}

    

4. Read 0x100 bytes from the start address 0x0001FFFF in the nonvolatile memory and store the data in pData:
   
   

   goal_maNvsRead(pMaNvsHdl, &desc, 0x0001FFFF, (uint8_t *)pData, 0x100);

LED

GOAL provides a media adapter for the controlling of LEDs. Standardized communication protocols often need status LEDs. The application can also use the LED media adapter to control LEDs application-specific. The media adapter for LEDs allows to handle

• single LEDS and

• groups of LEDs

The used hardware resources for the controlling of LEDs are encapsulated in the LED driver and depends on the platform. Details are described in the suitable GOAL Platform Manual. It is possible to control the LEDs via GPIOs or about a serial bus as IIC.
The media adapter provides the following functionality:

• open/close a media adapter for a single LED or a group of LEDs,

• get/set the state of a single LED,

• get/set the state of a group of LEDs.

The get-functions require, that the current LED state is readable from the platform.
The connection between the LED driver and the LED media adapter is identified by a MA-ID unique. The determination of the MA-ID is described in the suitable GOAL Platform Manual. The most LED drivers uses a MA-ID created by the application. The application has to assign single LEDs and/or groups of LEDs to MA-IDs during the platform initialization in the state GOAL_FSA_INIT.
A group of LEDs can consist of maximal 32 LEDs. The mask and state value have data type uint32_t and are bit-coded. Each LED in the LED group shall use the same bit position in the mask and state value. The interpretation of the bit values of the LED states is platform-specific. Maybe the application has to consider the polarity of the LEDs. The bit values for the mask are defined as follow:

Table: mask bit coding for groups of LEDs

Implementation guidelines

Switch on/off and get the state of a single LED

1. Define a MA-ID for a single LED:
   
   

   #define GOAL_MA_LED_APPL_SINGLE_LED 1

    

2. Call the LED driver function to initialize the LED hardware resource and to register the LED driver for a single LED to the LED media adapter in state GOAL_FSA_INIT.

3. Open a media adapter instance and get the MA-SPI handle:
   
   

   GOAL_MA_LED_T *pMaLedHdl; /*MA-LED handle */ goal_maLedOpen(GOAL_MA_LED_APPL_SINGLE_LED, &pMaLedHdl)

    

4. Switch on the LED:
   
   

   GOAL_MA_LED_STATE_T state = GOAL_MA_LED_STATE_ON; goal_maLedSet(pMaLedHdl, &state);

    

5. Get the current state of the LED:
   
   

   goal_maLedGet(pMaLedHdl, &state);

    

6. Close the media adapter instance:
   
   

   goal_maLedClose(pMaLedHdl);

Switch on/off and get the state of a LED group

A group of 32 LEDs shall be controlled.

1. Define a MA-ID for a group of LEDs:
   
   

   #define GOAL_MA_LED_APPL_GROUP_LED 2

    

2. Call the LED driver function to initialize the hardware resource for all LEDs and to register the LED driver for a group of LEDs to the LED media adapter in state GOAL_FSA_INIT.

3. Open a media adapter instance and get the MA-SPI handle:
   
   

   GOAL_MA_LED_T *pMaLedHdl; /*MA-LED handle */ goal_maLedOpen(GOAL_MA_LED_APPL_GROUP_LED, &pMaLedHdl);

    

4. Switch on the LEDs assigned to bit 31-24, do not change the LEDs assigned to bit 23-16, switch off LEDs assigned to bit 15-0:
   
   

   uint32_t mask = 0xFF00FFFF; uint32_t state = 0xFF000000; goal_maLedGroupSet(pMaLedHdl, &mask, &state);

    

5. Get the current state of all LEDs in the LED group:
   
   

   goal_maLedGroupGet(pMaLedHdl, &state);

    

6. Close the media adapter instance:
   
   

   goal_maLedClose(pMaLedHdl);

SPI

GOAL provides a media adapter for the SPI communication. The media adapter provides the following functionality:

• open/close a media adapter for a SPI-channel

• get/set a general SPI-configuration

• read data from the SPI-bus

• write data to the SPI-bus

• write and read data to/from the SPI-bus

• report events to higher layers

GOAL defines the following general SPI configuration settings:

Table: general SPI configuration settings

The SPI-configuration can be set by function goal_maSpiConfigSet(). The current SPI-configuration can be read by function goal_maSpiConfigGet(). The support of the SPI configuration settings depends on the SPI driver and the SPI controller. Details are described in the suitable GOAL Platform Manual.
SPI events are handled event-driven about an application-specific callback function. The supported events depend on the SPI driver and the availability on the SPI controller. GOAL provides the following events:

Table: general SPI events

The connection between the SPI driver and the SPI media adapter is identified by a MA-ID unique. The determination of the MA-ID is described in the suitable GOAL Platform Manual. The most SPI drivers determine the MA-ID by itself.

Callback functions

Table: Callback functions

Implementation guidelines

Read and write data via the SPI-bus

1. Call the SPI driver function to initialize the SI controller and to register the SPI driver to the SPI media adapter in state GOAL_FSA_INIT. During this guideline GOAL_MA_ID_SPI is used to mark the MA-ID. During the registration a unique MA-SPI handle is created.

2. Implement a callback function to handle SPI events:
   
   

   GOAL_STATUS_T cbApplMaSpiEvent(struct GOAL_MA_SPI_T *pMaSpiHdl, GOAL_MA_SPI_EVENT_T event, void *pArg) { … }

    

3. Open the media adapter, specify the callback function to handle SPI events and get the MA-SPI handle:
   
   

   GOAL_MA_SPI_T *pMaSpiHdl; goal_maSpiOpen(GOL_MA_SPI_ID, &pMaSpiHdl, cbApplMaSpiEvent, NULL);

    

4. Write 4 byte stored in pData to the SPI-bus:
   
   

   goal_maSpiWrite(pMaSpiHdl, (uint8_t *)pData, 4);

    

5. Read data from the SPI-bus and store the data to pData:
   
   

   uint16_t len; /* length of read data in bytes */ goal_maSpiRead(pMaSpiHdl, (uint8_t *)pData, &len);

    

6. Write 4 byte stored in pWriteData to the SPI-bus and read data from SPI-bus and store the read data to pReadData at the same time:
   
   

   uint16_t len; /* length of data to write as input parameter and length of read data as output in bytes */ len = 4; goal_maSpiWriteRead(pMaSpiHdl, pWriteData, pReadData, &len);

Configure the SPI interface

1. Get the current general SPI configuration of an opened MA:
   
   

   GOAL_MA_SPI_CONF_T spiConfig; goal_maSpiConfigGet(pMaSpiHdl, &spiConfig);

    

2. Specify SPI mode 0:
   
   

   spiConfig.mode = GOAL_MA_SPI_MODE_0;

    

3. Set SPI configuration:
   
   

   goal_maSpiConfigSet(pMaSpiHdl, &spiConfig);

Handle SPI events

1. Call the SPI driver function to initialize the SI controller and to register the SPI driver to the SPI media adapter in state GOAL_FSA_INIT. During this guideline GOAL_MA_ID_SPI is used to mark the MA-ID. During the registration a unique MA-SPI handle is created.

2. Implement a callback function to handle SPI events:
   
   

   GOAL_STATUS_T cbApplMaSpiEvent(struct GOAL_MA_SPI_T *pMaSpiHdl, GOAL_MA_SPI_EVENT_T event, void *pArg) { if (GOAL_MA_SPI_EVENT_ERR_OVERRUN == event) { … } else if (GOAL_MA_SPI_EVENT_ERR_PARITY == event) { … } else { /* handle unknown events application-specific */ } }

    

3. Open the media adapter, specify the callback function to handle SPI events and get the MA-SPI handle:
   
   

   GOAL_MA_SPI_T *pMaSpiHdl; goal_maSpiOpen(GOL_MA_SPI_ID, &pMaSpiHdl, cbApplMaSpiEvent, NULL);

    

4. If a SPI event occurs, the callback function cbApplMaSpiEvent is called.

TLS

GOAL provides a functionality for encryption and authentication of TCP packets on the base of the Transport Layer Security (TLS) protocol /TLS_RFC_5246/. The functionality of TLS requires:

• a TLS library,

• a GOAL driver for the integration of the TLS library into the GOAL system,

• a GOAL media adapter for TLS in order to use a generic interface for TLS in GOAL and.

• a GOAL media interface for TLS to handle TLS connections in a driver independent abstract layer.

GOAL allows to implement various libraries for cryptographic and transport layer security capabilities. The GOAL TLS media adapter makes it possible to exchange the TLS library with less effort. The TLS functionality is embedded into the GOAL core module for the network handling.
The TLS functionality comprises:

• encryption/decryption of TCP packets and

• the authentication by a X509-certificate.

The authentication is realized by a X509-certificate. The application can specify an own private key and an own X509-certificate by function goal_miTlsOpen(). The private key must have a length between 1024 bit and 2048 bit. If no X509-certificate is specified a default certificate is taken. The default certificate is port-specific.
The GOAL TLS media adapter allows:

• to open/close a GOAL TLS channel and

• to get information from the X509-certificate about the certification authority, the organization providing the web-server and the validity period

The encryption and decryption are made by the TLS library internally.

• example:

  • …\goal\appl\00410_goal\tls*

Configuration

The following compiler-defines are available to configure TLS:

• GOAL_CONFIG_TLS:

  • 0: TLS is disabled (default)

  • 1: TLS is enabled

mbed TLS library

GOAL supports the open source library mbed TLS. The following sources must be added to the compiler-project:

Table: mbed TLS libary

The GOAL driver for the mbed TLS library provides the following function for the registration to the GOAL TLS media adapter:

Table: goal_tlsMbedtlsInit

The application has to specify a MA-ID. There is no driver-specific rule for the construction of the MA-ID.
The execution of the algorithm for encryption/decryption needs some time and is processed in an own task to allow, that the algorithm can be interrupted by functions with higher priority. This method requires an operating system.
Further the application has to specify a MI-ID. This can be the same as the MA-ID This allows to switch between differnt TLS drivers more easily. The opening function of the GOAL TLS media is executed by function goal_miTlsOpen(). The application has to call the function goal_miTlsOpen() in the state GOAL_FSA_INIT_SETUP to initialize and to open the channels.
The function for getting information from the X509-certificate the GOAL TLS driver function is mapped to the function goal_miTlsReadInfo(). The function goal_miTlsReadInfo() is called by the application in the state GOAL_FSA_OPERATION.

Implementation guidelines

Initialize TLS

This example uses the mbed TLS library.

1. Define both a MA-ID and a MI_ID.

   #define APPL_MA_TLS_ID 1 #define APPL_MI_TLS_ID 1

    

2. Integrate the initialization of the GOAL TLS media adapter in the stage GOAL_STAGE_MODULES in application-specific function appl_setup(). Here a certificate structure may be given to the media adapter. If no is given, the media adapter uses a default certificate.

   GOAL_STATUS_T appl_setup (void) { goal_miTlsOpen(APPL_MA_TLS_ID, APPL_MA_TLS_ID, NULL); }

    

3. Create a GOAL net channel for the output of the GOAL TLS media adapter.

   GOAL_NET_CHAN_T pNetChanHdl; GOAL_NET_ADDR_T netChanAddr; GOAL_MEMSET(&netChanAddr, 0, sizeof(GOAL_NET_ADDR_T); addr.localPort = 443; goal_netOpen(&pNetChanHdl, &netChanAddr, GOAL_NET_TCP_LISTENER, NULL);

    

4. Configure the GOAL net channel as non-blocking.

   uint32_t optVal = 1; goal_netSetOption(pNetChanHdl, GOAL_NET_OPTION_NONBLOCK, &optVal);

    

5. Get the handle for the TLS session determined by the MI-ID and open the TLS channel.

   GOAL_NET_CHAN_T pTlsChanHdl; GOAL_MI_TLS_T *pMiTls; goal_miTlsGetById(&pMiTls, APPL_MI_TLS_ID); goal_miTlsSessionOpen(pMiTls, &pTlsChanHdl, pNetChanHdl);

    

6. Connect the GOAL net channel (TLS) to the GOAL net channel and specify a callback function to handle packets from the TCP client.

   goal_netOpenTunnel(NULL, pTlsChanHdl, applTlsClearDataCb, NULL, NULL);

    

7. Create a callback function to handle packets from the TCP client, see Chapter: Callback functions: cbNetFunc().

   void applTlsClearDataCb(GOAL_NET_CB_TYPE_T cbType, GOAL_NET_CHAN_T *pChan, struct GOAL_BUFFER_T *pBuf) { … }

Use a TLS channel

1. TCP/IP packets are transmitted and received encrypted. Only valid TCP/IP packages pass the TLS module.

2. Information from the certificate can be required.

   uint8_t certInfo[128]; goal_miTlsReadInfo(pTlsHdl, GOAL_CERTINFO_CA_CN, certInfo, 128);

CMFS

CMFS is a media interface working on top of the NVS media interface. It requires 2 serparate NVS regions for storing CM variables. Despite the plain CM implementation, which stores the whole CM variable store as a binary blob in flash, CMFS only writes modifications to the NVS region. Thereby the NVS region is sequientially written, thus a time consuming erase of the NVS region is not required. However if the NVS region is nearly fully written, the current state of variables is transferred to the secondary NVS region, where all continuing write operations take place.
This CMFS has some advantages over the plan CM implementation:

• NVS write operations can be performed much faster

• Data loss during reset while NVS is written can be omitted

To achive this, more NVS storage space needs to be reserved.

Integration of CMFS

Following except from goal_target_board.c shows integration of CMFS.

In order to utilize CMFS, the following configuration option must be enabled.

• GOAL_CONFIG_MEDIA_MI_CMFS:

  • 0: CMFS is not utilized (default)

  • 1: CMFS is utilized
    
    

This configuration option and the required files are added when the following feature is enabled in the Makefile, when using the GOAL build system:

Ethernet Frame Handler

Introduction

GOAL provides a Media Interface and Adapter for Ethernet based data exchange and protocols like HTTP or EtherCAT over Ethernet, see Figure 11.
The Ethernet Frame Handler in the Media Interface receives all Ethernet frames through the generic Ethernet Media Adapter and the Ethernet driver. The frame processing load can be reduced by activating the MAC address filtering by the compiler-define GOAL_CONFIG_MAC_ADDR_FILTER. Then only all broadcast/multicast and the own unicast Ethernet frames pass the MAC filter and are received. This is only a software filter, which drop packets not directed to the device.
The Ethernet Frame Handler identifies received Ethernet frames on base of the

• MAC address

• the Ether Type

The values for the Ether Type are standardized in IEEE 802.3. GOAL supports the following Ether Types:

• 0800h: IP Internet Protocol, version 4 (IPv4)

• 0806h: Address Resolution Protocol (ARP)

• 8100h: VLAN Tag

Other Ether Types are registeres by additional software components, such as the PNIO communication stack,
The Ethernet Frame Handler accepts all Ethernet frames if the Ether Type is set to GOAL_ETH_ETHERTYPE_ANY.
The kind of the identification is configured by function goal_miEthProtoAdd() or goal_miEthProtoAddPos().

The Ethernet frames can be divided in frames with low and high priority. The priority is also specified by function goal_miEthProtoAdd() or goal_miEthProtoAddPos(). The type of identification and the priority determine the handling of received frames, see Figure 12.

During the interrupt-controlled receipt the callback function specified by function goal_miEthProtoAdd() or goal_miEthProtoAddPos() is called immediately. For the loop-controlled handling the received message is stored internal and the callback function is called in the GOAL loop. The Ethernet Frame handler registers the function goal_miEthLoop() for this purpose.
Ethernet Frame HandlerEthernet controllers provide possibilities to analyze the Ethernet communication by counting of events represented as statistics, see Chapter: Statistics.
The generic Ethernet Frame Handler can be controlled via the command line interface, see Chapter Command line interface.

Configuration

Compiler-defines

The following compiler-defines are available to configure the generic Ethernet Frame Handler:

Table: Compiler-defines

CM-variables

The following CM-variables are available to configure the Configuration Manager:

Table: ETH_CM_VAR_MAC

Table: ETH_CM_VAR_LINK

Table: ETH_CM_VAR_SPEED

Table: ETH_CM_VAR_DUPLEX