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Not quite working - but just as expected
Posted by Chris
on
Wednesday, September 23, 2009
The moment of truth had arrived - a brand new PCB had been made up and installed onto the back of the Nokia shield. All that remained was to connect it to power and go out for a celebratory drink:
Check it out! Powered on and fired up! The screen looks lovely - it's taking its backlight power from the microchip (which in turn tells us that the MCU is working) but where's the little golfer bitmap and our opening menu?
The screen displayed a whole load of vertical lines and very little else.
At first this was a bit disappointing. But then we remembered that the first command in the ScoreSure device (after setting up the LCD and so on) is to draw the opening screen - and that means getting data from eeprom to use for drawing the bitmap.
The brand new eeprom on the PCB reads empty values as 255. So the device is drawing a sequence of 255 pixels in one colour, the flipping the background/foreground colours and drawing another line of 255 pixels. The bitmap routine draws pixels vertically (top-to-bottom) so when you think about it, if every value read back from eeprom is 255, it makes sense that the display shows just a whole bunch of lines and very little else.
How to get the bitmap to show?
That means connecting the device to a USB port and running the various custom-built apps to fill the eeprom with bitmap and menu data. Luckily, doing that shouldn't be too difficult: after all, we have a USB 4-pin header, ready to accept a USB connection.
The device connects and appears in the device manager as a valid USB/HID-compliant device. So all that remains is to drop the bitmap/menu data onto the eeprom chip.
That could be a job that takes ten minutes, or it might prove a bit tricky and take all night. It's not quite midnight as I'm typing this, so it looks like that's a job for the morning..........
Check it out! Powered on and fired up! The screen looks lovely - it's taking its backlight power from the microchip (which in turn tells us that the MCU is working) but where's the little golfer bitmap and our opening menu?
The screen displayed a whole load of vertical lines and very little else.
At first this was a bit disappointing. But then we remembered that the first command in the ScoreSure device (after setting up the LCD and so on) is to draw the opening screen - and that means getting data from eeprom to use for drawing the bitmap.
The brand new eeprom on the PCB reads empty values as 255. So the device is drawing a sequence of 255 pixels in one colour, the flipping the background/foreground colours and drawing another line of 255 pixels. The bitmap routine draws pixels vertically (top-to-bottom) so when you think about it, if every value read back from eeprom is 255, it makes sense that the display shows just a whole bunch of lines and very little else.
How to get the bitmap to show?
That means connecting the device to a USB port and running the various custom-built apps to fill the eeprom with bitmap and menu data. Luckily, doing that shouldn't be too difficult: after all, we have a USB 4-pin header, ready to accept a USB connection.
The device connects and appears in the device manager as a valid USB/HID-compliant device. So all that remains is to drop the bitmap/menu data onto the eeprom chip.
That could be a job that takes ten minutes, or it might prove a bit tricky and take all night. It's not quite midnight as I'm typing this, so it looks like that's a job for the morning..........
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