- on Test & Measurement
- Published in issue 4/2005 on page 0
SC Analyser 2005
Semiconductor Device Tester
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CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.
In the Components List on page 39, the order code for the programmed PIC (IC2) should be corrected to read: 030451-41.
Unfortunately, an early version of the PCB artwork is shown in Figure 5. Although it will produce a properly working instrument, the PCB design shown lacks the extra decoupling for the PLED display mentioned in the article. The PCB supplied through our Readers Services does have space and copper tracks for the extra decoupling network and comes with a corresponding note to customers.
Several readers have reported difficulties with the configuration bits to set up in the PIC. The confusion is owing to poorly defined standards at Microchip. Because all status bits are at ‘1’ with a new processor, there are options where ‘1’ means ‘enabled’, while for other options it means ‘disabled’. To add to the confusion, some programmer systems (including the one currently in use at Elektor labs) employ the notation ‘on’ and ‘off’.
The essential options are the oscillator, watchdog timer, low-voltage programming and in-circuit debugger. The following list provides the desired state for each option, where ‘0’ = unprogrammed and ‘1’ = programmed.
bit 13, CP: Flash Program Memory Code Protection bit; 1
bit 11, DEBUG: In-Circuit Debugger Mode bit; 1
bit 10-9, WRT1:WRT0 Flash Program Memory Write Enable bits; 11
bit 8, CPD: Data EEPROM Memory Code Protection bit; 1
bit 7, LVP: Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit; 1
bit 6, BOREN: Brown-out Reset Enable bit; 1
bit 3, PWRTEN: Power-up Timer Enable bit; 0
bit 2, WDTEN: Watchdog Timer Enable bit; 0
bit 1-0, FOSC1:FOSC0: Oscillator Selection bits; 11
R1,R5,R9 = 100k?, 1%
R2,R6,R10,R13 = 5k?6
R3,R7,R11 = 1k?, 1%
R4,R8,R12 = 100?, 1%
R14 = 47k?
R15 = 33?
R16 = 27?
P1 = 10k? preset
C1,C3 = 10µF 25V radial
C2,C5,C9 = 100nF
C4 = 100pF
C6,C7,C8 = 1nF MKT
C10 = 10µF 16V radial
D1 = 1N4001
IC1 = 78L05
IC2 = PIC16F876-20/SP (progeammed, order code 030451-41)
IC3,IC4,IC5 = 74HC4052 (HC only!)
S1 = on/off slide switch
LCD1 = standard LCD with 2x16 characters, e.g., ASI-G-162FS-GF-EWS/W (with backlight) or LCD 162C BL (P-LED with active backlight)
16-way SIL pinheader with mating connector, or flatcable for connection to display
JP1 = 2-way pinheader with jumper
3 mini croc clips
3 DIL16 IC sockets
1 DIL28 IC socket
Enclosure, e.g., Hammond 1591BTBU
9-V battery with clip-on leads
5 wire links
PCB, order code 030451-1
Disk, PIC hex code, order code 030451-11 or free download