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maelli01

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maelli01 last won the day on July 1 2017

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About maelli01

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  1. 2018: warming up my old thread ;-) good news: not a single crash in the last 4 months, 24/7 operation. I changed ISP and router box back in September. So I guess the TM4C1294 did not like my old router. With the new Fritzbox 7360 it works like a charm.
  2. it is classic LED multiplexing, rows and columns. I measured around 20mA in total when 3 digits are on, so this is an average current of around 1.2mA per LED (most numbers have around 5-7 segments on). Only one column driver is active high at a time, I go through the four of them with 64 Hz repetition, to avoid flicker. The "1s" are somewhat bright than the "fuller" numbers. For sure I would add resistors (at the segments, not the rows) if using a red or yellow display.
  3. An output power display for my solar system. G2553 Launchpad, Blue 4-digit LED display, RS485 Transceiver SN65HVD12P (a low power, 3.3V version of the standard SN75176), this is all there is. All pins are used, 4 + 7 for the multiplexed LEDs (no resistors: Blue LED, 3.6V supply, output resistance of the pins limit the LED current) 3 pins for UART and send/receive for the SN65. 2 pins for 32768Hz xtal (I had this one soldered in on the LP, so why not use it) The MSP asks the inverter over RS485/Modbus "what is your current output power". After less than half a se
  4. exactly, and the second diode to make it fool-proof
  5. Did anybody been succesful in writing to the SD card on the FR5994? For me the out of the box demo does not work for SD-logging. When re-installing it, no idea whether it worked when originally came out of the box ;-( Is there a "hello world on SD card" example using the fr5994 around somewhere? update: yesterday it did not work and I did not know why today I got it working (the out of the box project) and I do not know why.... ;-)
  6. The example msp430fr5994x_lpm4-5_02.c is supposed to show how little current is used in this mode. In the file it says: // MSP430FR5x9x Demo - Entering and waking up from LPM4.5 via P1.3 interrupt // with SVS disabled // // Description: Download and run the program. When entered LPM4.5, no LEDs // should be on. Use a multimeter to measure current on JP1 and // compare to the datasheet. When a positive voltage is applied // to P1.3 the device should wake up from LPM4.5. This will enable //
  7. Weekend-project: Autoranging microvoltmeter based on the MSP430FR4133 launchpad. ADC used: MIcrochip MCP3422, an 18bit, 3.75 sample/second Sigma Delta with 2 differential inputs. I2C interface This nice little chip contains a programmable amplifier (x2,x4,x8) and a not-too-bad internal reference of 2.048V. Max input range is +/-2.048V, resolution (8x amplified) is 2uV. Hand-etched a single layer PCB which goes on top of Launchpad. Type K cable in hot water: 2.93mV, 73Kelvin temp difference to ambient compare with my Fluke 289, 0.06% (datasheet says 0.05% typical, 0.35
  8. Hioki multimeter MSP430F449 8:12
  9. had this thing now running 24/7 for more than a year. Each time the ethernet library crashed, watchdog would trigger, count up one and restart the board. It crashed 32 times in the last 12 months. ;-) not often, but often enough to be a useless bit of kit. Has the problem been solved in the meantime? I have not been looking around in the forum much, but I have the impression that I am/was not the only one with issues. Could it make sense to upgrade to the latest energia?
  10. In the Horowitz/Hill Art of Electronics, third edition, design practices with discrete 74HCxxx, FPGA and Microprocessor are compared and discussed. As an example, the ultimate gibberish machine is described, a circuit that sends out a succession of pseudorandom bytes, as standard RS232 serial data, with 2 selectable speeds, 9600 / 1200 baud. Independent of the processor type, the implementation with a small micro and program it in C looks like the clear winner here, smallest engineering effort, lowest hardware effort (have to admit that I do not have the faintest idea about FPGA.) Th
  11. it is a long time ago since I hacked this together. For the LNK304 based 15V supply I more or less followed this: https://ac-dc.power.com/design-support/reference-designs/design-examples/der-231-132-w-power-supply/ Adapt R8 and R9 for different output voltage. The UF4007 is a cheap but rather fast diode, a normal 1N4007 will NOT work. I found this LNK chips very easy to use. But yes, these things handle high voltage without potential separation. I always use a separation transformer when experimenting and keep my hands im my pockets...
  12. sure you can power an MSP430 from 2 AA cells. The unequal power drain should be manageable for a hobby project. However, for a "product" it is probably not a too good idea: - what happens when inserting / removing batteries? - 2 cells discharged during months, 2 others not, might be o.k. for alkalines, but for long term using Nimh? I do not know. - The MSP can use the internal reference for battery voltage measurement. You have to check the datasheet whether the 1.5V reference works when 2 cells are at the end of life. - you might also check for wrong polarity. The german clever desig
  13. Last year my daughter (she was almost 7 back then) got interesting in soldering. So I let het solder stuff together, no function whatsoever. It did not last long, until she wanted to solder something that "does something". So I took the challenge and designed this christmas tree. - FR2 board, copper artwork by me, other side by my daughter. (cheap FR2 is better for using felt tip pens.. almost like paper) - G2553, all 16pins to simple LEDs, various colours - simple discrete regulator (another led+ transistor) for more or less 3V - powered by USB - mostly through-hole (soldered by
  14. Bike light follow-up: reverse engineering time! here is my almost complete circuit diagram. IC1 is a voltage regulator: 2.5V, exact type I could not find out. Only the MSP runs on the regulated voltage, all the rest runs from the raw battery voltage. Voltage divider R2 1M / R3 330K measure the battery voltage (some microamps get lost here) LED2 and 3 are indicator (red/green) LED1 is the power led PWM is 20kHz, coming from pin 11 of the MSP. Main switch is a Si4562, N and P channel 20V 5A mosfet. Inductor is 100uH. Instead of using only the upper fet, they alternately
  15. power an msp430 without power pins ;-) http://www.eevblog.com/2015/12/18/eevblog-831-power-a-micro-with-no-power-pin/
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