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Fixing alignment of 14-seg display multiplexation from Felipe Sanches (nw)

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This commit is contained in:
Scott Stone 2014-07-23 04:49:46 +00:00
parent 07e240eb3c
commit 867890321f
1 changed files with 17 additions and 1 deletions
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18
src/mess/drivers/minicom.c
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@ -27,6 +27,9 @@ Segment data is sent to each 14seg digit by first writing half of the data to po
Changelog:
2014 JUL 22 [Felipe Sanches]:
* Fixing alignment of 14-seg display multiplexation
2014 JUL 19 [Felipe Sanches]:
* Got the display working except for a few glitches
@ -126,7 +129,20 @@ WRITE8_MEMBER(minicom_state::minicom_io_w)
{
case 0x00:
{
m_p[offset]=data;
if (data != m_p[offset])
{
m_p[offset]=data;
//Bit P0.1 is the serial-input of a 20-bit shift register (made of a couple of chained UCN5810AF chips)
//We are emulating the display based on the assumption that the firmware will multiplex it by defining one digit at a given time
//It would be better (in terms of being closer to the actual hardware) to emulate the 20 bit shift register and update all digits
//for which a bit is TTL high. It seems to me that in the real hardware that would result in dimmer brightness in the display and it
//does not seem trivial to me to implement this using our current layout system. I'm leaving this note to whoever finds it exciting
//to explore these possibilities (perhaps myself in the future?).
if (BIT(data,1)){
m_digit_index = 0;
}
}
break;
}
case 0x01: