31 Jul 2010 7:13:48
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 Acqura now have Philips microcontrollers available for sale. If you need P89C668, P89C669, LPC76x or LPC900 family devices, check out our low MOQ's
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Take a look at our new forums. If you have a question about the 8xC51, LPC900, or MX families (or any 8051-related query) then ask your question here.
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| User laffelt has posted this comment in the General Forum |
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| LPC936 A/D or EEPROM problem |
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We have manufactured a product for several years which uses the P89LPC936 chip, currently there are over 1000 units in the field. Channels 2 & 3 on A/D converter 0 are used with an external multiplexor chip to read a four-wire resistive touchscreen. The touchscreen is calibrated here at the factory and the minimum and maximum x & y values are saved in the internal EEPROM. Those values are read on power-up and used to scale the touches into pixel values. The A/D converter is running at ~2.4MHz using the /3 divisor and we use the internal 7.3MHz clock for the main CPU clock, and it is set to continually scan channels 2 & 3.
We have now seen a low but significant qty of units returned from the field with touchscreen problems in two areas;
1- X or Y scaling problems (wrong functions are activated)
2- Difficulty detecting when nothing is touching the touchscreen. (s/b 0V)
The voltages on the A/D inputs look normal when compared to other units, even ones that have been in the field for several years. The A/D inputs have a 10k to ground to ensure that the inputs go to 0 with no touches and they also drain any capacitance between the two parallel plate (small but it is present). To read the touchscreen calibration values from the EEPROM I have to erase the flash sectors as the security bits are set. Once the program area is erased I can read the EEPROM values and they are within a few A/D counts of ideal. But now once I re-write the same program into the flash the product works perfectly!
The A/D converter is initialized as follows:
EADEE = 0; // No interrupts
ADMODA = 0x04; // Auto scan, continuous mode
ADMODB = 0x40; // Clock divisor = 3;
ADINS = 0x0C; // Channels 2 & 3
ADCON0 = 0x05; // Enable and start immediately
The EEPROM does not show data read errors in any other areas of the program that use it, and the EEPROM dummy read from the errata is in the init code even though Vcc rises much faster (~400uS) than the warning in the errata (10mS).
I am wondering if anyone has seen anything *remotely* like this or has any ideas.
Thanks!
Larry Affelt
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| Click here to see the whole discussion thread. |
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PDE51MX |
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PDS51E Daughterboard for P87C51Mx Devices |
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The PDE51MX daughterboard is a versatile bondout-based daughterboard which forms the basis for an affordable fully-featured in-circuit emulation system. In combination with a PDS51E motherboard it emulates all members of Philips 8051-derived P87C51Mx microcontroller family based on the Philips MX (Memory eXtension) core. It can also be used to emulate other sub-set microcontrollers including the 8xC51RA2/RB2/RC2/RD2 device families, and other similar devices from Philips and other manufacturers.
The PDE51MX system is supplied with a PLCC44 footprint adaptor compatible with a standard PLCC44 socket. Footprint adaptors for other packages types are in development.
The resulting emulation system allows complete control and tracing of execution of a user's program, and access to all registers and memory spaces of the target microcontroller, without consuming any device resources or introducing wait-states or other non-standard behaviour.
Features include:
- transparent real-time in-circuit emulation with execution trace.
- flexible motherboard + daughterboard + adaptor architecture.
- fast easy-to-install USB interface to host PC.
- sophisticated Windows debugger supporting all popular compilers.
- execution up to 30 MHz (6-clock P87C51Mx - 60MHz 12-clock equivalent).
- 256k bytes of emulation memory for user code.
- 128k x 64 bits real-time trace buffer with 12 digital input channels.
- Trace record includes values read from or written to SFR's.
- programmable PLL-synthesised clock frequency (25kHz - 100MHz, 0.1%).
- programmable supply voltage (2.7 - 5.5V in 25mV steps).
- multiple breakpoint sources, unlimited execution address breakpoints.
- trigger output for synchronising external equipment with execution.
NOTE: Execution speed is guaranteed to the rated frequency of for P87C51Mx devices (24 MHz at a 5V supply) but is tested during production to 30 MHz.
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