display board to interface it with 8051

74hc573 is used to store data so that the previous content on SS is not vanish when we disable LE pin. T0 select the proper latch 74hc238, 3x8 decoder is used. And to convert BCD into decimal, 74ls48 converter is used. Note that latches U1 to U4 are connected with C.C SS, so the output of 74ls48 will only go to these latches. Whereas latches U6 and U8 are connected to DP oF SS and LEDs respectfully. You can emit these latches i used them to distinguish between various mode i.e, digital clock, stop watch, counter and manual input...

8051 Generic Board is my fist project board in 8051 microcontroller course. This board is design for atmel 89c51 ic, please refer to its datasheet for more information. Now come towards board description: There are four i/o ports in 89c51, this board is design in such a manner that all ports are byte addressable whare as port3 can also be access bit wise in other world port 3 is also bit addressable. This can be done by proper selecting the jumper j2 and j5 and etc.Note that there are 8 jumpers at port 3 and also 8 jumpers at the u4 & u5 o/p pins are required, whereas in schematic only four are shown. 74ls245 latches are used to decide the direction of data. Switch SW1 is used to select the direction. If SW1 is towards vcc than the data direction is from 89c51 to latch o/p pins. And if SW1 is towards gnd than the direction is from latch to 89c51. For more info please refer to its datasheet. LED bargraph are used to indicate the status of 89c51 port pins; that is data in or out. Connectors J1, J4 and etc are used so that we can interface this board with other boards. Note that only port 0 and port 3 connections are shown in schematic; port 1 and port 2 connection are the same as of port 0, but in that case RP1 is not required. As port 0 needs to be pull up so, resistor pack, RP1, is only required for this port.

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