Gems LDS4, Operation Manual, Page: 46 / 71

40 LDS4 Colour Display System
© 2009 General Engine Management Systems Ltd. LDS4 Colour Display System
mean the split point is not triggered depending on vehicle speed and line taken. A value of 0.003
is a good starting point.
There are two outputs used to display the split information:
·
Split Number - The number of the last split passed. A split number of 0 indicates that the lap
start beacon was the last passed split.
· Split Lap Time - The time delta for the last split passed compared with the fastest lap. A
negative number indicates that the current lap is faster at this split.
7.5 LDS4 Brightness
The LDS4 brightness can either be set coarsly or finely.
The coarse control has eight brightness levels which can be selected by configuring an output to
produce a 0 to 7 value with 7 being brightest. This mode is adequate for single seater/ steering
wheel use where the display will be used in daylight conditions.
The fine control has 63 brightness levels which can be selected by configuring an output to
produce a value between 129 to 191 with 129 being the darkest, 191 the brightest and 160 the
default brightness value.
In either mode, the output could be connected to one of the analogue inputs for example to use a
rotary pot to control the brightness or it could be controlled from an ECU via the CAN. To setup
the brightness, select Setup | Brightness and select an appropriate output in the brightness tab.
If a fixed brightness is required, create a maths output whose equation is the brightness number
required and use this as the LDS4 brightness output.
Note: brightness levels 6 and 7 of the coarse mode brightness are overdriven for extra brightness
but this results in a loss of image contrast.
7.6 LDS4 Low Side Driver and PWM
The LDS4 has a low side driver (switched to ground) that can be used to drive a relay or other
item that is connected to a positive supply. To configure the low side driver, go to Setup | LDS4
Settings and select the Low Side Driver tab. Select an output to drive the low side driver - when
the output is greater than zero, the output will be on.
The low side driver can also be configured to be a PWM output as a special build request. In
order to enable this functionality, you will need to use the LDS4-PWM firmware and configure the
PWM options as follows:
Go to Setup | LDS4 Settings and select the PWM tab. Select an output to define the duty cycle.
This should be between 0 and 100 (the actual duty cycle supported in 2% to 98% - values outside
of this range will be constrained to this range). It is also necessary to specify the base frequency
in Hz. By ticking the Invert output box, the output of the PWM is inverted.
Note that using the LDS4-PWM firmware disables speed input 1.
7.7 LDS4 Calibrated Analogue Transmit
The LDS4 can transmit the first four analogue channels calibrated in a 1000 to 2000 range. This
can be useful if using the LDS4 analogue inputs as clutch paddles.
To configure this option, go to Setup | LDS4 Settings and select the Fast Analogue Tx tab. By
default, this option is on and transmits the data at around 1kHz on CAN ID 0x700. To turn off this