This made these systems expensive to produce and susceptible to interference and noise. For example, if the SPI slave is receiving many unserviced messages messages left pending in the operating systems buffer , a subsequent call to change the bitrate of I 2 C could fail in the following manner. The number of bytes written can be less than the requested number of bytes in the transaction due to the following possibilities. Between calls to the Aardvark API, these messages must be buffered somewhere in memory. An integer value, organized as a bitmask in the fashion described by AardvarkGpioBits. The phase option determines whether to sample or setup on the leading edge. This is due to operating system issues and the full-duplex nature of the SPI signaling.

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Aardvqrk that the last few bytes of the response may be corrupted as well. If the host PC does not have the appropriate driver installed, the operating system may prompt the user for the new driver upon completion of the firmware upgrade. There was an error reading from the Aardvark adapter.

USB Drivers – Linux v – Total Phase

Call the appropriate service function once for each type of data that is available. A status code indicating which types of asynchronous messages are available for processing.

For hardware versions prior to 2. The requested bitrate has most likely been set by the Aardvark device, but the response was lost. The following steps can help setup the correct permissions.

If the application design requires multi-threaded use of the Aardvark functionality, each Aardvark API call can be wrapped with a thread-safe locking mechanism before and after invocation.


If a timeout value outside this range is passed to the API function, the timeout will be restricted. Further data may be pending in the operating systems incoming receive buffer, but the function will not examine that data. Please note that once the Aardvark adapter detects a bus lock timeout, it will abort its I 2 C interface, even if the timeout condition is seen in the middle of a byte. The messages will be held until the appropriate API function is called. If the Aardvark adapter is directly plugged into a USB host controller, it can theoretically draw up to mA total, leaving approximately mA for any downstream target.

The only differences will be found in the calling convention of the functions. Since firmware version 2.

Aardvark I2C/SPI Host Adapter User Manual – Total Phase

Between calls to the Aardvark API, these messages must be buffered somewhere in memory. A combined status code from the write and the read operations is provided as the return value of the function.

This function returns the total number of bytes read from the slave which normally will be the same as the number of bytes written to the slave.

Only a partial number of bytes will be sent to the slave and only a partial number will be received from the slave; it is quite possible that these numbers will not be equal. I 2 C is a low-bandwidth, short distance protocol for on board communications.

The user of this API can manually assemble the first data byte if the hardware address programming feature with general call is required. If maxRxBytes is 0the slave can receive an unlimited number of bytes from the master.


Any modifications are at the user’s own risk. Alternatively, a split cable is available which connects to the ribbon cable and provides individual leads for each pin.

Slave Select — control line that allows slaves to be turned on and off via hardware control. If more bytes are requested in a transaction, the response string will be wrapped as many times as necessary to complete the transaction.

Each DLL revision is tagged as being compatible with firmware revisions greater than or equal to a certain version number. How does this work? All devices are connected through two wires: Distribution rights do not include public posting or mirroring on Internet websites. Upgrading the legacy firmware will cause the Aardvark unit to automatically switch to using the new communications driver interface.

For legacy systems, there are two different ways to access the Aardvark adapter, through USB hotplug or by mounting the entire USB filesystem as world writable.

Aardvark I2C/SPI Host Adapter

Hence, there could be multiple responses queued up from previous write transactions. An overflow can occur when the Aardvark aarvdark receives asynchronous messages faster than the rate that they are processed — the receive link is saturated. The best throughput can be achieved for single transactions that transfer a large number of bytes at a time.