Versions

• OS: Ubuntu 16.04
• Erlang: Erlang/OTP 20 Erts 9.2
• Rebar: rebar 3.5.3 on Erlang/OTP 20 Erts 9.2
• rebar3-grisp: master

Description

When a short message is sent before a longer message, the grisp_i2c module only transmits $SHORTMSGLENGTH bytes of the longer message correctly and 0x00 after that.

Reproduce:

• grisp_i2c:msgs([16#40, {write, <<16#23, 16#24, 16#25>>}]). works fine
• grisp_i2c:msgs([16#40, {write, <<16#42>>}, {write, <<16#23, 16#24, 16#25>>}]). What happens on the I2C bus: I2C_START to Address 40, I2C_WRITE, 0x23, 0x00, 0x00

Edit

The problem persisted even through several resets, but after connecting a debugger to take a look at the ATSAM's I2C registers, the problem mysteriously disappeared.