Board 50227

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Datasheet-display-50227-back.jpg Datasheet-display-50227-front.jpg

Seems similar to the 50229 board, but other display type (DLO1414 vs PD4435), other MCU (atmega161 where 50229 has a '162), and more buttons.

Seems like we have just 1 of this board. It might be similar to Bestand:IMG_8958.jpeg which then would be a second one.


4 extra buttons; wired between row 0/1, row 1/2 and col 1/2, col 2/3.

display mapping

6 displays (DLO1414) - mapped per below; with from left to right in each screen '3210'.


Displays zitten aangesloten volgens het voorbeeld uit de datasheet, op de 74HC138 rechtsboven de atmega161.

Display schematic 50227.

Echter, er worden meer enable-pinnen gebruikt dan in het voorbeeld schema. Zie onderstaande tabel. Tussen haakjes de namen uit de 74HC138 datasheet achter de namen uit het voorbeeldschema.

Atmega161 74hc138
pin 24 PC3 A (A0)
pin 25 PC4 B (A1)
pin 26 PC5 C (A2)
pin 27 PC6 G (E3)
pin 28 PC7 (nE1)
pin 16 PD6 nWR (nE2)

De datalijnen D0-D6 zitten op PA0-PA6 van de atmega161 (pin 39 PA0 tot pin 33 PA6)

reading the buttons

The 21 buttons are mostly in a 4x4 matrix. Every switch is between two MCU pins. The pins not fitting in the matrix are between 2 rows or 2 collumns.

The buttons 1, 2, 3 on the left are named 1, 2, 3 in the tables as well. The buttons labeled 1, 2, 3 on the right are labeled 1' 2' 3' as these are not in parallel with the others labeled 1, 2, 3.

row/col PD2 PD3 PD4 PD5
PB3 36C 2' 3 04
PB2 24 18C 1 2
PB1 27 36R 36L 1'
PB0 HELI 09 18L 18R

The keys that are between 2 row lines or between 2 collumn lines can be re-fitted in another matrix: (Possibly other configurations are possible and maybe even more efficient! By choosing other row/col lines in software for the same hardware)

row/col PD5 PB2 PD3 PB0
PD4 3' . EXEC .
PB3 . CORR . .
PB1 . 22 . 06

The keys are thus NOT the same als on 50229.

Read as any other keyboard matrix (? Enable pull-ups on input row/col s & unused col/row and drive one col/row low ?)


Todo! (Might be different from 50229 also... Though same circuit with a 74hc138 and 74hc174 seems to have been applied, it might be connected to different IO lines compared to 50229... )