Dai Yokota
TC77 --- SPI Thermal Sensor
TC77 SPI thermal(temperature) sensor chip
ライブラリを公開する手順の練習を兼ねて、サンプルプログラムとして公開していた物からライブラリ部分を分離してみました。
温度センサの TC77 を使うためのライブラリです。 SPIなのにIOが共通になっているという変わったチップです。
MOSIとMISOを抵抗で繋いでしまうというのがポイントで、それさえ解れば難しいトコはありません。
pin connection
mbed TC77
MOSI ---R 10K---+
|
MISO -----------+--- SI/O
SCK --------------- SCK
CS --------------- CS(active low)
Revision 0:b8fa872b60e6, committed 2016-06-10
- Comitter:
- jk1lot
- Date:
- Fri Jun 10 14:27:27 2016 +0000
- Commit message:
- first published version
Changed in this revision
| TC77.cpp | Show annotated file Show diff for this revision Revisions of this file |
| TC77.h | Show annotated file Show diff for this revision Revisions of this file |
diff -r 000000000000 -r b8fa872b60e6 TC77.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/TC77.cpp Fri Jun 10 14:27:27 2016 +0000
@@ -0,0 +1,55 @@
+#include "TC77.h"
+
+TC77::TC77(SPI *s, PinName pin):spi(s),cs(pin)
+{
+ cs=1;
+ spi->format(16);
+ spi->frequency(100*1000);
+ start();
+}
+
+void TC77::start(void)
+{
+ write(0x0000);
+ //shutdownモードからの復帰には最大400ms掛かる（データシートより）
+ wait_ms(400);
+}
+
+uint16_t TC77::id(void)
+{
+ shutdown();
+ int16_t v=write(0x0000);
+ wait_ms(400);
+ return v;
+}
+
+float TC77::temperature(void)
+{
+ int16_t t0=read();
+ //bit2が0のときは測定が終わっていないので値は不正
+ while((t0&0x0004)==0) {
+ wait_ms(400);
+ t0=read();
+ }
+ return ((signed int)t0>>3)*0.0625f;
+}
+
+//TC77は読み取りと書込みが同時には出来ない
+//16bit読み込むと次の16bitが書込みになる
+int16_t TC77::write(int16_t command)
+{
+ cs=0;
+ int16_t v=spi->write(0x0000);
+ spi->write(command);
+ cs=1;
+ return v;
+}
+
+//読むだけならば16bitのやり取りで良い
+int16_t TC77::read(void)
+{
+ cs=0;
+ int16_t v=spi->write(0x0000);
+ cs=1;
+ return v;
+}
diff -r 000000000000 -r b8fa872b60e6 TC77.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/TC77.h Fri Jun 10 14:27:27 2016 +0000
@@ -0,0 +1,73 @@
+/*
+ * TC77 SPI Thermal Sensor
+ *
+ * mbed TC77
+ * MOSI ---R 10K---+
+ * |
+ * MISO -----------+--- pin1 SI/O.
+ * SCK --------------- pin2 SCK.
+ * CS --------------- pin7 CS(active low).
+ *
+ */
+
+#ifndef TC77_H
+#define TC77_H
+
+#include "mbed.h"
+
+/** TC77 SPI Thermal Sensor chip
+ *
+ * @note pin connection
+ * @code
+ * mbed TC77device
+ * MOSI ---R 10K---+
+ * |
+ * MISO -----------+--- pin1 SI/O
+ * SCK --------------- pin2 SCK
+ * CS --------------- pin7 CS(active low)
+ * @endcode
+ *
+@note sample program
+@code
+#include "mbed.h"
+#include "TC77.h"
+
+SPI spi1(p5,p6,p7);
+TC77 tc77(&spi1, p8);
+
+int main() {
+ while(true) {
+ printf("%.1f \r\n",tc77.temperature());
+ wait(1.0);
+ }
+}
+@endcode
+*/
+class TC77
+{
+ SPI *spi;
+ DigitalOut cs;
+public:
+ //! @param s pointer to SPI object
+ //! @param pin PinName of CS
+ TC77(SPI *s, PinName pin);
+
+ //! go to shutdown mode(power save)
+ inline void shutdown(void) {write(0xffff);}
+ //! start from shutdown mode
+ void start(void);
+ //! get device ID
+ uint16_t id(void);
+ //! get temperature @return Temperature value, expressed in degrees Celsius
+ float temperature(void);
+protected:
+ //! read data and send command.
+ //! It is impossible in the TC77 to perform the writing and reading at the same time.
+ //! After reading 16bit, TC77 is ready to write. So total transferred bit is 32.
+ int16_t write(int16_t command);
+ //! read data.
+ //! transferred 16bit only
+ int16_t read(void);
+};
+
+#endif
\ No newline at end of file