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Increase SDA2 and SCL2 until 1Mb/sec

Topic last updated 02 Aug 2015, by tom dunigan. 1 reply
Carlos Rodriguez
26 Aug 2014

Hi everybody,

I'm using the platform LPC1768 for an extress test for a chip. According with the mbed's spec for LPC1768 in the SDA2/SLC2, can't be configured like an Fast Mode Plus, to get 1Mbit/sec, it's possible just with SCA0/SLC0, if I'm not wrong. But, Does it exist any way to increase the speed in SDA2/SCL2 until 1Mbit/Sec?

I have seen in the manual that the registers SDADRV0 AND SCADRV0 should be enabled, but it doesn't make difference, i suppose that it's just for I2C0.

Thanks,

Carlos

tom dunigan
02 Aug 2015

Chapter 19 of reference manual says only I2C0 can be configured for 1 Mbs, but I2C0 pins P0.27 and P0.28 are not connected on the mbed LPC1968 PCB. So unless you are working an standalone LPC1768, you can't run I2C at 1mbs. Also there is no code in targets/hal/TARGET_NXP/TARGET_LPC176X/i2c_api.c that manipulates the I2CPADCFG register.

With logic analyzer and I2C on P27/P28, I confirmed 100khz and 400khz speeds. If I requested 1mhz, analyzer showed I2C clock at 800 khz, so you do get a speedup (and I2C seemed to still be working with BMP085).