FEASA LED ANALYSER
ICT VERSION
In-Circuit Test Mode
Capture LED Data (HSI or WSI or xyI) PWM LED's
This function will capture the Frequency Data of all the LED's that are controlled by Pulse Width
Modulation (PWM) and store this data in memory ready for output. PWM LED's are switched on
and off rapidly to control the LED Intensity. The PWM_bar (pin 8) signal is pulled up on the
Analyser. The timing for this function is shown in Figure 14b.
Figure 14b.
The timing sequence is as follows:-
1/
Drive WE_bar High, Drive OE_bar and PWM_bar Low. RyBy_bar (pin18) will be
driven low by the Analyser.
2/
Select the Capture Range you require (Figure 12) and Drive the address bus to this
code. (00000) for Auto Capture
3/
Drive WE_bar Low and the Analyser will drive RyBy_bar High. All the frequencies
(from the previous capture) will be turned off at this time. After the time T
capture
RyBy_bar will be driven low by the Analyser to indicate it is ready for the next
function. The time for T
capture
will vary depending on the range selected. The test system
should loop on the RyBy_bar signal and wait for it to go low.
4/
Drive WE_bar High any time after RyBy_bar has gone Low.
27
WE_bar
OE_bar
Addr
Capture Address Code 0X15 - 0X1B
RY_BY
t
capture
Fout
WE_bar
OE_bar
Addr
RY_BY
t
capture
Fout
WE_bar
OE_bar
Addr
RY_BY
t
capture
Fout
PWM_bar
PWM_bar