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Electronics => Beginners => Topic started by: f618x on January 17, 2023, 08:10:10 am

Title: Finicky Touch IC Holtek BS816A-1 Rechargeable Lamp Controller
Post by: f618x on January 17, 2023, 08:10:10 am

Hey, I made quite an unwieldy post a few days earlier (https://www.eevblog.com/forum/beginners/rechargeable-led-light-controller-pcb/) that covered multiple sub-systems on my custom PCB for a rechargeable LED lamp project. So I'm breaking down each issue into its own thread. Anywho,

Setup:
The controller currently uses a Holtek BS816A-1 which I chose for its price and six channels- one channel per spike via an additional PCB and one attached to a standoff connecting to the body (this channel fails to pick up a change in state). The touch IC attaches to the spike PCB via a 5P PH JST cable. I'm using a pico RP2040 for an MCU and TP4056 as a charge controller for protected 18650 LiPos. The body of the lamp is nickel-plated aluminium, and the spikes are Rhodium-plated copper. To isolate the body I've made a few 3D-printed parts.

Code:
The code waits for a high signal from either of the touch channels 1-5. On a quick press it turns on the LEDs. On a long press, with the LEDs on, It rises the brightness, using PWM.

Issue:
I'm picky when it comes to touch controls, there's nothing I hate more than a finicky one-while the touch subsystem works; it doesn't work flawlessly.

• The touch is not as responsive as I'd like it to be
• On battery the touch becomes even less responsive
• Occasional phantom long-press-touches that rise the brightness (never short presses?!)

(https://d2w9rnfcy7mm78.cloudfront.net/19827353/original_5d4be81cfff496da4880288f905a439e.png?1673602773?bc=0)
(https://d2w9rnfcy7mm78.cloudfront.net/19827722/original_ccf4e572be9aa5ab7dfce0b937bf7527.png?1673605561?bc=0)
(https://d2w9rnfcy7mm78.cloudfront.net/19886707/original_31ef6bab03e58b62af3f68d26878f931.png?1673941945?bc=0)
(https://d2w9rnfcy7mm78.cloudfront.net/19827434/original_ee205397789bcc7e640534dc088de114.jpg?1673603617?bc=0)
(https://d2w9rnfcy7mm78.cloudfront.net/19827800/original_9fdf9fa18fe69dbb6ab838d63d1c9454.png?1673606042?bc=0)

Proposed Redesign:
I am thinking to use a single-channel touch IC, Tontek TTP233D, for all 5 channels to reduce the risk of phantom touches. I also hope this increases the sensitivity but I'm just guessing. I am still planning on using the 5P PH JST cable and the same touch-spike PCB since I have them on hand. Would running one channel through 5 cables to 5 individual touch pads work? Here's how I imagine the change in layout (also subbing out the RP2040 due to power concerns)

(https://d2w9rnfcy7mm78.cloudfront.net/19827764/original_2f1bcdfd465d1fa1a34db471e88da7e5.png?1673605758?bc=0)
(https://d2w9rnfcy7mm78.cloudfront.net/19827721/original_8f1ff0aa0d401c4509206afdb95b2e58.png?1673605561?bc=0)

 :scared:

Please let me know what you think,