Write pointer register increasing after first read without sending anything

Question

I am observing something strange, when I first read Sn_TX_WR it reads 0, but then if I wait 1s and read it again it throws a random number like 24578, 45171. The device isn’t sending anything and no commands are written to it. I tested a litte bit more and when doing 50ms pause between the reads the value increases after 4 read, so that happens after about 200ms. Here is log generated by my device: [2.34] {3} eth_channel_write: free: 2048, nr: 3 [2.34] {3} eth_channel_write: start: 0, nr: 3 [2.40] {3} eth_channel_write: start: 0, nr: 3 [2.46] {3} eth_channel_write: start: 0, nr: 3 [2.52] {3} eth_channel_write: start: 0, nr: 3 [2.58] {3} eth_channel_write: start: 10841, nr: 3 [2.64] {3} eth_channel_write: start: 10841, nr: 3 [2.70] {3} eth_channel_write: start: 10841, nr: 3 [2.76] {3} eth_channel_write: start: 10841, nr: 3 [2.82] {3} eth_channel_write: start: 10841, nr: 3 [2.88] {3} eth_channel_write: start: 10841, nr: 3 In [ ] is the system uptime in sec. start is the Sn_TX_WR and nr is the socket number. Why does that happening? Should it stay at 0 when not sending anything?

becky · Answer

This is normal. Sn_TX_WR register is set to RANDOM value after INIT. When data is transmitted, this value is increased by the transmitted size.