Raspberry Pi2でws2812bを使う

この人のライブラリを使えば動くけど、レジスタアクセスは多分volatileを追加したほうが将来コンパイラが変わっても安心。

https://github.com/richardghirst/rpi_ws281x#

C-cで終了すると終了処理が走らないのでmain.cにSIGINTを追加。ついでにSIGTERMも。

ほかにもmailbox.cにおいてレジスタをmmapでマッピングするのは正しく動くけどunmapにバグがあるので修正して使っています。

差分はこんな感じ。

RPi2からWS2812Bへの接続は直接接続でやってます。安全のため100Ωの抵抗を直列に挟んでいます。(抵抗による電圧降下はなかったです）

diff rpi_ws281x-master/dma.h rpi_ws281x-master_new/dma.h
42,48c42,48
<     uint32_t ti;
<     uint32_t source_ad;
<     uint32_t dest_ad;
<     uint32_t txfr_len;
<     uint32_t stride;
<     uint32_t nextconbk;
<     uint32_t resvd_0x18[2];
---
>     volatile uint32_t ti;
>     volatile uint32_t source_ad;
>     volatile uint32_t dest_ad;
>     volatile uint32_t txfr_len;
>     volatile uint32_t stride;
>     volatile uint32_t nextconbk;
>     volatile uint32_t resvd_0x18[2];
55,56c55,56
< {
<     uint32_t cs;
---
> {
>     volatile uint32_t cs;
71,72c71,72
<     uint32_t conblk_ad;
<     uint32_t ti;
---
>     volatile uint32_t conblk_ad;
>     volatile uint32_t ti;
88,90c88,90
<     uint32_t source_ad;
<     uint32_t dest_ad;
<     uint32_t txfr_len;
---
>     volatile uint32_t source_ad;
>     volatile uint32_t dest_ad;
>     volatile uint32_t txfr_len;
93c93
<     uint32_t stride;
---
>     volatile uint32_t stride;
96,97c96,97
<     uint32_t nextconbk;
<     uint32_t debug;
---
>     volatile uint32_t nextconbk;
>     volatile uint32_t debug;
rpi_ws281x-master_new/だけに発見: dma.h~
rpi_ws281x-master_new/だけに発見: dma.o
diff rpi_ws281x-master/gpio.h rpi_ws281x-master_new/gpio.h
36,61c36,61
<     uint32_t fsel[6];                            // GPIO Function Select
<     uint32_t resvd_0x18;
<     uint32_t set[2];                             // GPIO Pin Output Set
<     uint32_t resvd_0x24;
<     uint32_t clr[2];                             // GPIO Pin Output Clear
<     uint32_t resvd_0x30;
<     uint32_t lev[2];                             // GPIO Pin Level
<     uint32_t resvd_0x3c;
<     uint32_t eds[2];                             // GPIO Pin Event Detect Status
<     uint32_t resvd_0x48;
<     uint32_t ren[2];                             // GPIO Pin Rising Edge Detect Enable
<     uint32_t resvd_0x54;
<     uint32_t fen[2];                             // GPIO Pin Falling Edge Detect Enable
<     uint32_t resvd_0x60;
<     uint32_t hen[2];                             // GPIO Pin High Detect Enable
<     uint32_t resvd_0x6c;
<     uint32_t len[2];                             // GPIO Pin Low Detect Enable
<     uint32_t resvd_0x78;
<     uint32_t aren[2];                            // GPIO Pin Async Rising Edge Detect
<     uint32_t resvd_0x84;
<     uint32_t afen[2];                            // GPIO Pin Async Falling Edge Detect
<     uint32_t resvd_0x90;
<     uint32_t pud;                                // GPIO Pin Pull up/down Enable
<     uint32_t pudclk[2];                          // GPIO Pin Pull up/down Enable Clock
<     uint32_t resvd_0xa0[4];
<     uint32_t test;
---
>     volatile uint32_t fsel[6];                            // GPIO Function Select
>     volatile uint32_t resvd_0x18;
>     volatile uint32_t set[2];                             // GPIO Pin Output Set
>     volatile uint32_t resvd_0x24;
>     volatile uint32_t clr[2];                             // GPIO Pin Output Clear
>     volatile uint32_t resvd_0x30;
>     volatile uint32_t lev[2];                             // GPIO Pin Level
>     volatile uint32_t resvd_0x3c;
>     volatile uint32_t eds[2];                             // GPIO Pin Event Detect Status
>     volatile uint32_t resvd_0x48;
>     volatile uint32_t ren[2];                             // GPIO Pin Rising Edge Detect Enable
>     volatile uint32_t resvd_0x54;
>     volatile uint32_t fen[2];                             // GPIO Pin Falling Edge Detect Enable
>     volatile uint32_t resvd_0x60;
>     volatile uint32_t hen[2];                             // GPIO Pin High Detect Enable
>     volatile uint32_t resvd_0x6c;
>     volatile uint32_t len[2];                             // GPIO Pin Low Detect Enable
>     volatile uint32_t resvd_0x78;
>     volatile uint32_t aren[2];                            // GPIO Pin Async Rising Edge Detect
>     volatile uint32_t resvd_0x84;
>     volatile uint32_t afen[2];                            // GPIO Pin Async Falling Edge Detect
>     volatile uint32_t resvd_0x90;
>     volatile uint32_t pud;                                // GPIO Pin Pull up/down Enable
>     volatile uint32_t pudclk[2];                          // GPIO Pin Pull up/down Enable Clock
>     volatile uint32_t resvd_0xa0[4];
>     volatile uint32_t test;
rpi_ws281x-master_new/だけに発見: gpio.h~
rpi_ws281x-master_new/だけに発見: libws2811.a
rpi_ws281x-master_new/だけに発見: linux.pyc
diff rpi_ws281x-master/mailbox.c rpi_ws281x-master_new/mailbox.c
76a77,78
>    unsigned offset = (unsigned)addr % PAGE_SIZE;
>    addr-=offset;size+=offset;
rpi_ws281x-master_new/だけに発見: mailbox.c~
rpi_ws281x-master_new/だけに発見: mailbox.o
diff rpi_ws281x-master/main.c rpi_ws281x-master_new/main.c
150a151,152
>     sigaction(SIGINT , &sa, NULL);
>     sigaction(SIGTERM, &sa, NULL);
194c196
<         usleep(500000);
---
>         usleep(1000*1000/15);