FAQ
TL;DR: PIC n’ MIX is a flexible, worklab-style series where parts are added over time; expect add‑ons like a ~£5 2.4" SPI TFT. “as soon as I am happy that it will work.” [Elektroda, Anonymous, post #21679422]
Why it matters: If you’re planning parts and budgets, this FAQ shows what to buy now and what to expect later—without surprises.
Quick Facts
- Series format: exploratory worklab, not a fixed BOM; parts may change between installments. [Elektroda, Anonymous, post #21679419]
- Display add‑on: TJCTM24024‑SPI 2.4" ILI9341 SPI TFT recommended for the graphics stage. [Elektroda, Anonymous, post #21679424]
- Typical display cost: Approx. £5 when sourced from eBay/China. [Elektroda, Anonymous, post #21679422]
- ADC/FFT reference build: 10 kHz sampling using Timer3 ISR with Microchip DSP library linked. [Elektroda, Anonymous, post #21679423]
- UK delivery note: Farnell non‑trade orders often show £3.95 delivery or £20 minimum. [Elektroda, Anonymous, post #21679421]
Is there a complete components list and how many parts are in the series?
No fixed master list exists. The series is deliberately exploratory, so parts can change as lessons evolve. The editorial stance is that resourcefulness is part of the learning. The exact number of parts isn’t disclosed, and installments may include updates or optional upgrades. Plan for a core PIC setup plus add‑ons like a TFT display later. “PIC n MIX isn’t a structured constructional project in our traditional style.” [Elektroda, Anonymous, post #21679419]
Which graphics display should I buy for the PIC n’ MIX project?
Use the TJCTM24024‑SPI 2.4" TFT with ILI9341 controller and SPI interface. It’s the module the author validated for the graphics installment. A 3.2" variant was ordered for testing and might also work, but the 2.4" is the safe choice today. If you want to minimize risk, wait for confirmation on larger panels before purchasing. [Elektroda, Anonymous, post #21679424]
How much does the TFT add‑on cost?
Expect about £5 for the 2.4" SPI TFT when sourced via eBay from China. That price helps keep the overall project budget modest while adding meaningful visualization capability. The author indicated he would publish the exact part once verified, aligning with the series’ validate‑then‑buy rhythm. [Elektroda, Anonymous, post #21679422]
How do I link the Microchip DSP library in MPLAB X for the FFT build?
Add the library at the linker stage.
- Right‑click the project and open Properties.
- Under XC16‑LD, choose Option Categories → Libraries, then add “DSP”.
- Save, rebuild, and verify the linker includes the DSP library.
This resolves FFT symbol references during linking. [Elektroda, Anonymous, post #21679423]
What sampling rate and trigger setup works for the A/D to feed the FFT?
A reference build used Timer3 to trigger ADC conversions at 10 kHz via an ISR. The input was a TLC555CP astable replacing a 1 kHz synthetic square wave from Microchip example CE482. This configuration produced meaningful spectra after feeding stored samples into the FFT routine. [Elektroda, Anonymous, post #21679423]
Which way round does the 10 µF coupling capacitor go?
The final guidance is to orient it opposite to the original note due to changed bias points. The author confirmed the correction after comparing op‑amp and microphone DC biases. He also recommends using a non‑polarized 10 µF MLCC to avoid polarity concerns. [Elektroda, Anonymous, post #21679429]
What 10 µF non‑polarized capacitor type is recommended?
A 10 µF X7R MLCC (e.g., 6.3 V, 0805) works well. The author favors ceramics for their lower leakage current, which helps battery‑powered builds. Quote: “The main benefit with ceramics... is that they have a lower leakage current.” This also avoids electrolytic polarity edge‑cases. [Elektroda, Anonymous, post #21679429]
I keep losing my forum replies—any workaround while posting updates?
Copy your text to the clipboard before submitting in case CAPTCHA fails. The editor reported occasional crashes and uses this safeguard. Until fixed, drafting offline or in a text editor also prevents content loss during retries. [Elektroda, Anonymous, post #21679419]
Do Farnell orders have free delivery for hobbyists?
One user reports the site showing free delivery for trade only, otherwise £3.95 or a £20 minimum order. Factor that into cost planning if you prefer Farnell for logistics like UPS. Prices and policies vary by region and account type. [Elektroda, Anonymous, post #21679421]
Will a larger 3.2" TFT work instead of the 2.4"?
A 3.2" display was ordered for testing and might work, but it wasn’t yet confirmed. The author advised waiting for his report before buying the larger screen. For now, the TJCTM24024‑SPI 2.4" remains the validated option. [Elektroda, Anonymous, post #21679424]
Does the July installment actually deliver a working graphics build?
Yes—teaser feedback stated it works very well. This aligns with the series cadence where validation precedes part recommendations. For scheduling context, a reader noted the July issue was expected in shops by June 7 of that year. [Elektroda, Anonymous, post #21679425]
What is PIC n’ MIX, and who is it best for?
PIC n’ MIX is a worklab‑based tutorial series, not a fixed construction project. It suits learners who enjoy experimenting, iterating, and sourcing parts as features mature. Expect occasional updates or changes based on practical findings. “Part of the package… is the need for resourcefulness.” [Elektroda, Anonymous, post #21679419]
