Rotary encoder and tact switches issue (not activable)

Rotary encoder and tact switches issue (not activable)

Postby ottone » Tue Mar 19, 2019 8:30 am

I have some issues on rotary encoder and on function switches.

Only two first switches works (V/DIV and SEC/DIV). Instead, when I press TRIGGER or OK switch, nothing seems happening.

Similary, when I rotate the encoder, no changes are seen (sometimes, a single step of V or SEC happen). ADJ function works.
I thinked that was due to activation, but activation (SEC/DIC+TRIGGER+ADJ) isn't possible because TRIGGER malfunction (I also tried with a firmware downgrade, with same results).

Referring to this schema
if I measure
1 ) Check to make sure no opens between the following pin pairs. The resistance between these pin pairs should read about 1K.
DB0 ---- to ---- encoder pin 1
DB1 ---- to ---- encoder pin 3
DB3 ---- to ---- encoder pin 4

I obtain right value.

But if
2 ) Check to make sure no shorts between ground and pin 1, 3, and 4 of the encoder. Resistance between these pins to ground should be greater than 10K. NOTE: At certain positions of the encoder pin 1 & 3 are connected to pin 2 (which is ground) internally. If you find both pin 1 & 3 read zero resistance to ground you just need to turn the encoder by one position to make the internal connections open.

the resistance is greater than 10k (12k) only between pin 4 and ground. Between others two pins 1 and 3 (and ground) is approximately 8k.

3 ) Check the pull-up resistors R23, R24, and R25. Measure the resistance between pin 1, 3, & 4 and +3.3V respectively. The result should read about 10K for each pins.

similary, between pin 4 and +3.3V is 11k, but between pin 1 and 3 (and +3.3V) is 6.6k

All 3 pull-up resistors are 01C (10k); R5, R6 and R7 are 1k (01B). How is should be.

Similary, if for the switches I measure the pull up resistance, I obtain:
DB4 <-> +3.3V 10k
DB5 <-> +3.3V 10k
DB6 <-> +3.3V 5.4k (!)
DB7 <-> +3.3V 5.4k (!)

DB4 <-> GND 11k
DB5 <-> GND 11k
DB6 <-> GND 6.7k
DB7 <-> GND 6.7k

measured with switches not pressed;
DB4 is wired to V/DIV
DB5 is wired to SEC/DIV
DB6 is wired to TRIGGER
DB7 is wired to OK

Any idea or suggestion? Some DBx I/O lines of micro that are fault?

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