SWI Commands
BEGIN
Starts the Atmel SWI host on the given IO pin. The SWI protocol can be used on any of the IO pins, however it is especially convenient to use it on IO0 and IO2 as the internal pullup resistor can be used thus eliminating the need for an external pullup resistor.
Start the SWI host: SWI0 BEGIN [pin] [pull]
Parameters:
The pin parameter can be set to any of the IO pins 0, 1, 2, 3, or 4.
The pull parameter can be omitted if not using the internal pullup resistors or set to PULL to enable the pullup resistor (available on channels 0 and 2).
Response:
This function returns an ACK Response if the command succeeds in starting the SWI host on the desired IO pin. If the command fails, the function will return a NAK Response.
Example Usage:
TOKEN
This command is used to send either a WAKE, ONE, or ZERO token, as defined by the Atmel SWI specification. Note that due to the timing constraints of the protocol, the delay between communication with the host adapter and the PC may prohibit the construction of full data packets by stringing together ZERO and ONE tokens strung together with this command. For actual data packet transmission, use the PACKET command.
Send Token: SWI0 TOKEN [type]
Parameters:
The type parameter can be set to the following values:
to send a Wake token, use
WAKEto send a Zero token, use
ZEROor0to send a One token, use
ONEor1
Response:
This function returns an ACK Response if the command succeeds in sending the token. If the command fails, the function will return a NAK Response.
Example Usage:
FLAG
This command transmits a flag as defined by the Atmel SWI protocol. Note that this command is simply using the TX command below to send the predefined byte value of each of the four flags.
Transmit an SWI flag: SWI0 FLAG [flag]
Parameters:
The flag parameter can be set to either COMMAND, TRANSMIT, IDLE, or SLEEP.
Response:
This function returns an ACK Response if the command succeeds in transmitting the SWI flag. If the command fails, the function will return a NAK Response.
Example Usage:
PACKET
This command is used to construct and transmit full data packets as defined by the Atmel SWI protocol. This command features a number of sub-commands. The typical flow is to set the OPCODE, set PARAM1 and PARAM2, then set the DATA. At this point, send the packet using the SEND subcommand and then finally CLEAR it and start preparing the next packet to send.
OPCODE
This subcommand is used to set the OPCODE byte of the packet: SWI0 PACKET OPCODE [code]
Parameters:
The following is a complete list of the supported opcodes that can be used for the code parameter:
DERIVEKEYDEVREVGENDIGHMACCHECKMACLOCKMACNONCEPAUSERANDOMREADSHAUPDATEEXTRAWRITEGENKEYINFOTEMPSENSEVERIFYSIGN
Response:
This function returns an ACK Response if the command succeeds in setting the opcode. If the command fails, the function will return a NAK Response.
Example Usage:
PARAM1
This subcommand is used to set the PARAM1 byte of the packet: SWI0 PACKET PARAM1 [data]
Parameters:
The data parameter accepts an 8-bit integer (byte) value.
Response:
This function returns an ACK Response if the command succeeds in setting the PARAM1 value. If the command fails, the function will return a NAK Response.
Example Usage:
PARAM2
This subcommand is used to set the PARAM2 bits of the packet: SWI0 PACKET PARAM2 [data]
Parameters:
The data parameter accepts a 16-bit integer value.
Response:
This function returns an ACK Response if the command succeeds in setting the PARAM2 value. If the command fails, the function will return a NAK Response.
Example Usage:
DATA
This subcommand is used to set the payload data of the packet.
To load 1 byte of data: SWI0 PACKET DATA [data]
To load up to 64 bytes of data from BUF[n] into the payload: SWI0 PACKET DATA BUF[n] [count]
Parameters:
The data parameter accepts an 8-bit integer (byte) value.
In the case of using the buffer to load data, the count parameter can be from 1 to 64.
Response:
This function returns an ACK Response if the command succeeds in setting the payload value. If the command fails, the function will return a NAK Response.
Example Usage:
CLEAR
This command clears the OPCODE, PARAM1, PARAM2, and DATA fields of the packet: SWI0 PACKET CLEAR
Parameters:
This command has no parameters.
Response:
This function returns an ACK Response if the command succeeds in clearing the packet data. If the command fails, the function will return a NAK Response.
Example Usage:
SEND
This command sends the constructed packet: SWI0 PACKET SEND
Parameters:
This command has no parameters.
Response:
This function returns an ACK Response if the command succeeds in sending the packet. If the command fails, the function will return a NAK Response.
Example Usage:
TX
This command transmits a byte of data as defined by the Atmel SWI protocol.
Transmit a byte: SWI0 TX [data]
Parameters:
The data parameter is the 8-bit integer (byte) value to be transmitted.
Response:
This function returns an ACK Response if the command succeeds in transmitting the byte. If the command fails, the function will return a NAK Response.
Example Usage:
RX
This command receives n bytes of data as defined by the Atmel SWI protocol.
Transmit a byte: SWI0 RX [count]
Parameters:
The count parameter is the number of bytes to receive up to a max of 255.
Response:
This function returns an ACK Response if the command succeeds in receiving the bytes. If the command fails, the function will return a NAK Response.
Example Usage:
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