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The P89LPC900 (2)

practical application

In this second instalment we will look at the actual application of this microcontroller in greater detail. Notably the ‘in system programming’ functionality is described in detail. In addition, a practical design is presented that not only functions as a programmer for the controller, but as a prototyping board as well. As an example project, guided by an application note from Philips, a very good ADC can be built without requiring any additional peripherals.Flash memoryMany of you will recognise the ceramic microcontroller with a glass window. These are the UV erasable versions that were (and sometimes still are) used during the debugging stage of the application software. An expensive solution indeed, but the alternative, the burning of one-time programmable (OTP) devices was often more costly and far from flexible. The arrival of multi-time programmable flash (MTP) has made the UV-erasable type mostly obsolete. With that, the relatively long UV erasure time is now also a thing of the past.
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Extra info, Update
In the circuit diagram and on the PCB, the RTS line is connected to pin 9 of 9-way sub-D connector K6. However, RTS should be connected to pins 7 and 8. The PCB layout has been modified accordingly (free download from our website).
Resistors:
R1 = 100k?
R2,R3,R10 = 10k?
R4...R7 = 47k?
R8,R9 = 1k?
R11 = 390?
R12 = 270?
R13 = 4k?7
P1 = 100? preset V
Capacitors:
C1 = 33nF
C2,C5-C10,C12,C16,C17 = 100nF
C3,C4 = 22pF
C11,C13,C15 = 100µF 25V radial
C14 = 10µF 16V radial
Semiconductors:
D1 = 1N4001
D2,D3 = low-current LED
T1 = BC557
IC1 = P89LPC932BA
IC2 = MAX3222CPN
IC3 = 74HC02
IC4 = ULN2003
IC5 = LM317T
Miscellaneous:
JP1,JP2 = jumper
K1 = 8-way SIL pinheader
K2,K5 = 4-way SIL pinheader
K3 = 5-way SIL pinheader
K4 = 6-way SIL pinheader
K6 = 9-way sub-D socket (female), PCB mount
K8 = 2-way PCB terminal block, lead pitch 5mm
S1 = pushbutton, one make contact
X1 = 11.0592MHz quartz crystal
PCB, available from The PCBShop
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