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.
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.
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.
|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). Er is bij dit type display geen D7.
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 (C0)||PD3 (C1)||PD4 (C2)||PD5 (C3)|
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 (C3)||PB2 (R2)||PD3 (C1)||PB0 (R0)|
The keys are thus NOT the same als on 50229.
Keys in the matrix are read by setting all row/col pins to input, setting pull-ups on all collumns but leaving rows open. Then one by one set rows low and read collums.
An identical circuit with a 74hc138 and 74hc174 seems to have been applied, as on 50229, connected to the same I/O lines. Because there are more LED's, port A5 is also used for an extra bit.
PORTA 0 downto 5 is used to load LED data into the 74HC174 flipflops, a 74HC183 is used to select which of the flipflops is put through to the leds. On 50227 there are 21 LED's. The unused last 3 inputs of the 4th flipflop are held high.
To enable the demux that is driving the flipflop clock:
- nE1 connects to PC6 - drive LOW to enable LED's
- nE2 connects to PC7 - drive LOW to enable LED's
- E3 connects to PC5 - drive HIGH to enable LED's
The adress lines are as folows (This selects which one of the flipflops/registers is put trough to the leds)
- A0 connects to PC3
- A1 connects to PC4
- A2 connects to PD6
The flipflop datalines:
- D0 connects to PA0
- D1 connects to PA1
- D2 connects to PA2
- D3 connects to PA3
- D4 connects to PA4
- D5 connects to PA5
So this is how to drive the LED's:
- Drive all adress lines (PC3,4 & PD6) low, so none of the clock inputs is driven.
- Put data on PA0..5 as per below table
- Choose 74hc174 as per below table
- Set adress lines such that the 174 gets a rising clock edge so it clocks the data to the LED's
|74HC174 nummer :||0||1||2||3|