Looking at Learning PIC programming

Sorry I forgot to dsay I would like to be able to program it from my computer:)

Ta Merlin

as

I use the very simple JDM programmer. Details of my verion are here:

Leon

as

have lots of pic projects / info sources

David F. Cox

as

Or buy a kit like the ones

The dontronics simmstick kits are good just use a zif socket for the programmer, makes it easy and you dont have to worry about damaging the pins.

Alex

I have a Tektronix TDS220 oscilloscope that has developed this intermittent startup fault:

Sometimes when the power is switched on the LCD will only show a random number of horizontal dark/brihter lines of random widths. The LCD backlight will not be turned on and the mainborad doesn't appear to be working as there will be no 1KHz/5V square wave on the compensation probe output. Also the GPIB interface will not be working. After I reset the mainboard (switch off and on the oscilloscope) several times I eventually manage to get it started and the oscilloscope will work fine for then on, until it is switched off. So I suspect this might be related to a power on reset function (firmware) not being called properly at the startup or maybe some dodgy power supply connection to the main board. I wonder if anyone has had a similar problem and/or could provide some insight about what might be causing this problem. Tektronix UK will charge £425 + VAT (US$775 + tax) to fix it and will take nearly 1 month (apparently they have to be sent to Germany to be repaired). Thanks.

Tony

I have a Tektronix TDS220 oscilloscope that has developed this intermittent startup fault:

Sometimes when the power is switched on the LCD will only show a random number of horizontal dark/brihter lines of random widths. The LCD backlight will not be turned on and the mainborad doesn't appear to be working as there will be no 1KHz/5V square wave on the compensation probe output. Also the GPIB interface will not be working. After I reset the mainboard (switch off and on the oscilloscope) several times I eventually manage to get it started and the oscilloscope will work fine for then on, until it is switched off. So I suspect this might be related to a power on reset function (firmware) not being called properly at the startup or maybe some dodgy power supply connection to the main board. I wonder if anyone has had a similar problem and/or could provide some insight about what might be causing this problem. Tektronix UK will charge £425 + VAT (US$775 + tax) to fix it and will take nearly 1 month (apparently they have to be sent to Germany to be repaired). Thanks. Tony

I have a Tektronix TDS220 oscilloscope that has developed this intermittent startup fault:

Sometimes when the power is switched on the LCD will only show a random number of horizontal dark/brihter lines of random widths. The LCD backlight will not be turned on and the mainborad doesn't appear to be working as there will be no 1KHz/5V square wave on the compensation probe output. Also the GPIB interface will not be working. After I reset the mainboard (switch off and on the oscilloscope) several times I eventually manage to get it started and the oscilloscope will work fine for then on, until it is switched off. So I suspect this might be related to a power on reset function (firmware) not being called properly at the startup or maybe some dodgy power supply connection to the main board. I wonder if anyone has had a similar problem and/or could provide some insight about what might be causing this problem. Tektronix UK will charge £425 + VAT (US$775 + tax) to fix it and will take nearly 1 month (apparently they have to be sent to Germany to be repaired). Thanks.

Tony

This will be hard to debug if it's really intermittent. But, as I recall from opening my TDS210, these models use an off-the-shelf 16/32-bit Motorola micro for which datasheets should be readily available. Trace back the reset line and see what it runs to. Maybe an RC reset circuit, and maybe the C is bad.

Or the CPU may not be getting clock.

It's also possible that the micro is starting up just fine, but that its first act is to wait for something else in the circuit to come up - and that something else may be the culprit. You need to scope the CPU to see if it is wiggling its address lines while in this hung state. Some 68K microprocessors [don't know about microcontrollers] also require an end-of-cycle signal to complete external memory access cycles. The CPU will hang if it doesn't get this signal - so again, see what the input is doing.

Thanks for your helpful suggestions. If there is no clock then the problem should be easier to solve.

Tony