# Qiangli 32x32 P10 panel with LS9931CS+DP32020A-B - no output on RP2040 **URL:** \ **Category:** Uncategorized\ **Created:** [February 9, 2026, 5:51am UTC](https://rpi-rgb-led-matrix.discourse.group/t/qiangli-32x32-p10-panel-with-ls9931cs-dp32020a-b-no-output-on-rp2040/1186 "2026-02-09T05:51:20Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![aknsha](https://avatars.discourse-cdn.com/v4/letter/a/74df32/32.png) [@aknsha](https://rpi-rgb-led-matrix.discourse.group/u/aknsha)\ **Post date:** [February 9, 2026, 5:51am UTC](https://rpi-rgb-led-matrix.discourse.group/t/qiangli-32x32-p10-panel-with-ls9931cs-dp32020a-b-no-output-on-rp2040/1186/1 "2026-02-09T05:51:20Z")
**Panel specifications:** - Size: 32x32 pixels (P10 indoor module) - Driver ICs: LS9931CS (LED driver) + DP32020A-B (row decoder) - Address lines: A, B, C connected; D pin present but grounded on panel - HUB75 interface (standard 16-pin connector) - Photo of back: [attach your photo] **Previous working configuration:** I have another Qiangli 32x32 panel with DP5135+RUL5158C chips that works perfectly using DMD\_STM32 library with: - 3 address pins (A, B, C), D grounded - Shift register multiplexing configuration - 1/8 scan pattern **Current problem:** New panel with LS9931CS+DP32020A-B gives completely black screen (no output at all) with same configuration. **What I’ve tried:** 1. Standard 1/8 scan configuration with 3 address pins (A, B, C) - no output 2. Plain 1/16 scan with 4 address pins (A, B, C, D connected to GPIO) - no output 3. Various DMD library patterns: RGB32x32plainS16, RGB32x32\_S8\_Qiangli, RGB32x32\_S8\_maxmurugan - none work 4. Both regular DMD\_RGB and DMD\_RGB\_SHIFTREG\_ABC wrapper - no difference 5. Verified all pin connections, OE, SCLK, RGB pins - all correct **Hardware:** - Microcontroller: RP2040 (Raspberry Pi Pico) - Library: DMD\_STM32 (ported for RP2040) - Pin assignments: A=GPIO6, B=GPIO7, C=GPIO8, D=GPIO9 (when connected) **Questions:** 1. Does DP32020A-B require D pin to be actively driven for 32x32 1/8 scan, or should it remain grounded? 2. Is LS9931CS+DP32020A-B combination fundamentally different addressing than DP5135+RUL5158C requiring different scan pattern? 3. Any known working configurations for this specific IC combination? Any guidance would be greatly appreciated. ![image](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/902804b3c35007e5706a3081e357d74660946b57.jpeg) ---
**Author:** ![board707](https://avatars.discourse-cdn.com/v4/letter/b/bc79bd/32.png) [@board707](https://rpi-rgb-led-matrix.discourse.group/u/board707)\ **Post date:** [February 9, 2026, 8:38am UTC](https://rpi-rgb-led-matrix.discourse.group/t/qiangli-32x32-p10-panel-with-ls9931cs-dp32020a-b-no-output-on-rp2040/1186/2 "2026-02-09T08:38:35Z")
Hi @aknsha > [@aknsha](#): > > Does DP32020A-B require D pin to be actively driven for 32x32 1/8 scan, or should it remain grounded? NO, it doesn’t require D pin. The DP32020 is a multiplexer of shift register type, that needs only three pins (A B C) to manage a panel with any scan number. > [@aknsha](#): > > Is LS9931CS+DP32020A-B combination fundamentally different First of all, the driver LS9931 is a new type sPWM driver, that use a fundamentally different principle of operation. This driver is not supported by the library. Moreover, the datasheet for the LS9931 chip is not publicly available, making code development difficult. > [@aknsha](#): > > Any known working configurations for this specific IC combination? I don’t know any of them. ---
**Author:** ![aknsha](https://avatars.discourse-cdn.com/v4/letter/a/74df32/32.png) [@aknsha](https://rpi-rgb-led-matrix.discourse.group/u/aknsha)\ **Post date:** [February 16, 2026, 5:56am UTC](https://rpi-rgb-led-matrix.discourse.group/t/qiangli-32x32-p10-panel-with-ls9931cs-dp32020a-b-no-output-on-rp2040/1186/3 "2026-02-16T05:56:35Z")
Turns out they need an unlocking sequence that the vendor is not willing to share, maybe to promote their LED driving software.