User's Manual

P330 Data Sheet / User Guide 27
DRAFT
4.4.5 CAN
The CAN interface is provided with a TI SN65HVD231 CAN line driver. That driver provides a 5
volt differential signal. For additional details on the driver, a link is provided to the TI part. The
maximum data rate is 1 Mbps. http://www.ti.com/lit/ds/symlink/sn65hvd231.pdf
Time Domain’s application note 320-0326 CAN Interface Application Note provides additional
information on the software interface. This document is available on the Time Domain website.
4.4.6 Detection of Failures
When the P330 is powered, it will boot and execute a series of self-diagnostic checks. This process
takes approximately 10 seconds. At the end of this process the unit will respond to commands issued
by the Host. If the unit has failed to boot, then there will be no communications. If the unit has failed
self-diagnostics, it will set the “BIT Results” parameter to a non-zero number and attempt to function
normally. “Attempting” to function normally does not guarantee that the unit will actually function
properly. Therefore, it is a good practice for the Host computer to initiate communications with the
P330 by first checking the BIT Results. (This is accomplished with the Status Info Message. See the
API for details.) If the returned parameter is not zero, the unit should be power-cycled.
4.5 GPIO
The P330 has fifteen user-definable general purpose input/output (GPIO) pins. Most of these pins
operate on 3.3 Vdc but there are several that operate at 1.8 Vdc. Approximately half come from the
ARM processor and the remaining ones are connected to the FPGA. These pins can be defined as
inputs, outputs, or as having a special function. The SPI pins are special function pins. If the user
chooses not to use the SPI interface, then the SPI pins can be reallocated for general use. The state
and direction of these pins are controlled through the software API.
GPIO output pins can be used to source 1mA of current per pin. Do not exceed this limit. Exceeding
this limit will damage the P330.
The GPIO pins are not associated with a specific connector but are instead distributed through the
various connectors. Some GPIO pins are available from multiple connectors. Figure 4-15 lists the
various GPIO pins and their associated connector and pin number.
As of this date, there is currently no software support (i.e. API commands) for controlling the state of
the GPIOs. Similarly, the function of the SPI lines is currently fixed such that these lines can only be
used for SPI. Time Domain expects to provide expanded support for GPIOs in an upcoming
software release.