296
FLD controller
2.7.2 FLD operation (FLD automatic display and key-scan using segments)
The FLD controller can choose functions from those listed in Table 2.7.1. The circled items are described
in detail below. Figure 2.7.7 shows the operation timing, and Figures 2.7.8 to 2.7.10 show the set-up
procedures.
Table 2.7.1. Selectable functions
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Note 1: When selecting the FLD blanking interrupt, any one of 1
Tdisp, 2
Tdisp, or 3
Tdisp can be selected as
Tscan time.
Note 2: When selecting the gradation display mode, make sure to use 16-timing as the timing number.
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Operation (1) The FLD starts an automatic display when both the automatic display control bit and the
display start bit are set to “1”.
(2) The display data, the contents from the first address through the last address, in the FLD
automatic display RAM for each port is output to each port. The last address is the result of
decreasing the number indicated in the FLD data pointer from the first address. The grada-
tion display control data is arranged at an address which is calculated by subtracting “70
16
”
from the stored address in the FLD automatic display RAM of the corresponding timing and
pin. Bright display is performed by setting “0”, and dark display is performed by setting “1”.
However, the contents of the FLD automatic display RAM for ports P5
0
, P5
1
, and P6
0
to P6
7
are disabled by selection of the digit pulse output function, and the digit pulses are automati-
cally output.
(3) The FLD data pointer counts down during Tdisp time. When the count reaches “FF
16
”, the
pointer is reloaded and starts counting over again.
(4) The FLD interrupt request bit is set to “1” simultaneously with the falling edge of the last
timing. The FLD automatic display output is turned off for a duration of 1
Tdisp, 2
Tdisp,
or 3
Tdisp, depending on post-interrupt settings. During this time, key scanning, which
makes use of FLD segments, can be applied.
(5) During FLD automatic display, the FLD automatic display can be interrupted by writing “0” to
the display start bit.