VDI-RODERICO

[roderico]

very nice video and VDI, could you show a picture of the magnetic stones that gives you +84? how do you shift X and Y by 90 degrees to see what the effect of the shifting is? SW3 only works when the vdi is idle, i.e. it won't work when it is busy e.g. near a target, and the backlight is only on for 0 < VDI < upper_limit i.e. all negative values are discarded in the firmware unless there is some interest of turning the backlight on for negative values... however it can be implemented since there is now plenty of space.
I can upload a LCD firmware for the PIC18F25K22 if you already have the pcb to test if it works like the one you have with PIC16F886 and if so then test a glcd version (you can reuse the same pcb)...

[kroman01]

photo of a stone that gives +84 reading ... it's easy to distinguish them from typical finds in static mode with zero ground is eliminated

is PCB. PIC16F25K22 and GLCD with KS0108 controller have. I am ready to make a prototype

[roderico]

I have some questions about the stone, do you know what mineral this rock has? does it act as a magnet when you approach a small piece of iron? and what is the VDI value you have for a silver and/or an aluminum coin?

[roderico]

I have also compiled the LCD version for the PIC18F25K22, the attached zip file has two test firmwares that were built with two different compilers, the XC8 in free mode and the SDCC which has no restrictions, could you test them on the fields? it will be good to see if the first one is equivalent to the PIC16F886 firmware that you have already tested and/or if there are any problem with the SDCC firmware...

[kroman01]

I do not know what a stone is, what a mineral, but a strong magnet attracts it very poorly
the PCB will be assembled as soon as possible

[kroman01]

do I connect the LCD in 8 bit mode as in the previous version with PIC16F886

[roderico]

yes, it is the same for both

[kroman01]

pcb board is assembled and works with two firmware ... it looks like it's ok ... what I should pay attention to when testing in the field

[roderico]

you should look for any difference with respect to PIC16F886, any malfunction, etc. and compare the two firmwares, which one is better, worse or if there is no difference...

[kroman01]

two firmware work well, checked on the same hardware, give stable readings, the only problem I have with raising positive indications, brass coins have +43, reducing the shift in the x and y channels increase positive readings, but reduce the degree of discrimination

[roderico]

ok very good, I think this might be related to your modification of the shifting of XY channels by 90 degrees which I don't understand, I get the same vdi value (+86) with a silver coin of 34mm diameter and 2mm thickness as the stone you showed

[kroman01]

the only difference I noticed in connection with software 1.4 is the faster saving of settings in memory.
what phase shift is needed in X and Y

[roderico]

my coil RX and TX signals are shifted by 90 degrees so I guess I would get the same vdi values as you if the same calibration is used for the vdi (e.g. with a small piece of foil)

[kroman01]

I connected VDI to PIC16F690 with 1.4 software and I see that there is a significant difference compared to new systems that are faster, especially in the case of PIC18F25k22

[roderico]

PIC18 are better (and more expensive in general), however, this is mainly due to drive the LCD in 8-bit mode, in 4-bit mode you need double work and time to send just one character to the LCD