117
In order to pass a number to the Power Control Lines, it is converted into binary
and the digits are passed to the serial data input of the shift register (Ds) from pin 2 of
the parallel port. The chip is signaled to input a bit at each digit through the shift
register clock input (SHcp) from pin 4 of the parallel port. After the shift register has
been filled the storage register clock input (STcp), connected to pin 5 of the parallel, is
signaled to send the contents of the shift register to the output latches, which connect
to the Power Control Lines of the TMS. Figure 3 shows an example of setting the power
level to 83%.
9TX>,r>'>? 7∙∕7∙W∙>n Register ' ' ∣ ∣ Output 9¾99<pw' I ∙>'>γγy??? ∣ Latdies ....... ∣.....∣ DS ! |
??????oi ' τt'>m'n ' ' I |
777770101 77777777 1 |
77770∣01 * 777777TJ I |
77701010 1 77010100 ' I 1 77977777 ∣ γHTTΓH ' .. .... ι -. ι I I |
70101001 OlOIObll * I I ТУГУГУТ} I . I ....... I......I __________J___________ |
oιoιooιι ' 00000000 01010011 1 01010011 I I ___________________________I_____________________________ | |
I |
I |
ΓTr^πT.......,...Γ.....Γ∣Γ.ΓΓΓΓ.ΓΓΓΓΓΓΓΓΓ,,.,.,,.,.,l | |||||
I I |
I |
Γ I |
I |
I I I | |||
SHcp ;n ; |
----------- I |
---------------- I |
------------- I _____L |
-- I — I |
------------ I ------------- I |
I | |
I I ST 1 1 blCP I I |
_ I I |
I I _______L |
I I |
I I I I __________________________I I |
I I I I I I |
I | |
~~] 1 I | |||||||
I I MR 1 < _____________________ I__________________ I |
I |
I I |
I I |
I I I I _________ I_______________L |
I I I I ..... I____________ ⅜ |
I lΓ~l _____________________11 I | |
I1 1 1 rι ∙∙t I l |
-------------, |
............. 1" I |
.............. T I |
--------------------------1 I I I |
," 1 1 J1 ■........... I I l |
1 Ir v ■ I |
Figure 3 Control diagram of the control box. This example shows the steps to set the TMS strength to
83%, or 010100112 in binary. The inputs Ds, SHcp, STcp, and MRcorrespond to pins 2,4,5,and 6 of the
computer's parallel port when connected.
Bypassing safety systems for manual control and adding safety systems for computer
control